Codeforces: 877E. Danil and a Part-time Job

Problem Link : http://codeforces.com/contest/877/problem/E

Solution Idea:

    Run a dfs on the given for getting the Euler tour order or inorder traversal order. Then the tree is converted to a liner 1D array. Now we can apply range query and update on this array.

    Now use a range update query data structure. Here I have used segment tree. Now initialize the tree with the initial value and now our job is to just toggle a subtree of the given tree and perform query operation. Use a propagation for the update and answer the query.



#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#define pii              pair <int,int>
#define pll              pair <long long,long long>
#define sc               scanf
#define pf               printf
#define Pi               2*acos(0.0)
#define ms(a,b)          memset(a, b, sizeof(a))
#define pb(a)            push_back(a)
#define MP               make_pair
#define db               double
#define ll               long long
#define EPS              10E-10
#define ff               first
#define ss               second
#define sqr(x)           (x)*(x)
#define D(x)             cerr<<#x " = "<<(x)<<endl
#define VI               vector <int>
#define DBG              pf("Hi\n")
#define MOD              1000000007
#define CIN              ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define SZ(a)            (int)a.size()
#define sf(a)            scanf("%d",&a)
#define sfl(a)           scanf("%lld",&a)
#define sff(a,b)         scanf("%d %d",&a,&b)
#define sffl(a,b)        scanf("%lld %lld",&a,&b)
#define sfff(a,b,c)      scanf("%d %d %d",&a,&b,&c)
#define sfffl(a,b,c)     scanf("%lld %lld %lld",&a,&b,&c)
#define stlloop(v)       for(__typeof(v.begin()) it=v.begin();it!=v.end();it++)
#define loop(i,n)        for(int i=0;i<n;i++)
#define loop1(i,n)       for(int i=1;i<=n;i++)
#define REP(i,a,b)       for(int i=a;i<b;i++)
#define RREP(i,a,b)      for(int i=a;i>=b;i--)
#define TEST_CASE(t)     for(int z=1;z<=t;z++)
#define PRINT_CASE       printf("Case %d: ",z)
#define LINE_PRINT_CASE  printf("Case %d:\n",z)
#define CASE_PRINT       cout<<"Case "<<z<<": "
#define all(a)           a.begin(),a.end()
#define intlim           2147483648
#define infinity         (1<<28)
#define ull              unsigned long long
#define gcd(a, b)        __gcd(a, b)
#define lcm(a, b)        ((a)*((b)/gcd(a,b)))

using namespace std;

//using namespace __gnu_pbds;
//typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;


/*----------------------Graph Moves----------------*/
//const int fx[]={+1,-1,+0,+0};
//const int fy[]={+0,+0,+1,-1};
//const int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const int fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const int fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move
/*------------------------------------------------*/

/*-----------------------Bitmask------------------*/
//int Set(int N,int pos){return N=N | (1<<pos);}
//int reset(int N,int pos){return N= N & ~(1<<pos);}
//bool check(int N,int pos){return (bool)(N & (1<<pos));}
/*------------------------------------------------*/

#define mx 200005
#define segment_tree int l=n*2,r=l+1,mid=(b+e)/2
pii info[mx];
vector<int>g[mx];
int cnt=0;
int maps[mx],ara[mx];

void dfs(int u, int par)
{
    info[u].ff=++cnt;
    maps[cnt]=u;
    for(int i=0;i<SZ(g[u]);i++)
    {
        int v=g[u][i];
        if(v==par) continue;
        dfs(v,u);
    }
    info[u].ss=cnt;
}

struct data
{
    int val, prop;
};

data tree[3*mx];

void push_down(int n, int b, int e)
{
    if(tree[n].prop%2)
    {
        segment_tree;
        tree[l].val=(mid-b+1)-tree[l].val;
        tree[l].prop++;
        tree[r].val=(e-mid)-tree[r].val;
        tree[r].prop++;
        tree[n].prop=0;
    }
}

void init(int n, int b, int e)
{
    if(b==e)
    {
        tree[n].val=ara[maps[b]];
        tree[n].prop=0;
        return;
    }
    segment_tree;
    init(l,b,mid);
    init(r,mid+1,e);
    tree[n].val=tree[l].val+tree[r].val;
}

void update(int n, int b, int e, int i, int j)
{
    if(b>j || e<i) return;
    if(b>=i && e<=j)
    {
        tree[n].val=(e-b+1)-tree[n].val;
        tree[n].prop++;
        return;
    }
    push_down(n,b,e);
    segment_tree;
    update(l,b,mid,i,j);
    update(r,mid+1,e,i,j);
    tree[n].val=tree[l].val+tree[r].val;
}

int query(int n, int b, int e, int i, int j)
{
    if(b>j || e<i) return 0;
    if(b>=i && e<=j) return tree[n].val;
    push_down(n,b,e);
    segment_tree;
    int p=query(l,b,mid,i,j);
    int q=query(r,mid+1,e,i,j);
    return p+q;
}

char str[10];

int main()
{

//    freopen("in.txt","r",stdin);
//	  freopen("out.txt","w",stdout);

    int n;
    sf(n);
    for(int i=2;i<=n;i++)
    {
        int a;
        sf(a);
        g[a].pb(i);
    }

    for(int i=1;i<=n;i++) sf(ara[i]);
    dfs(1,1);
    init(1,1,n);
    int q;
    sf(q);
    while(q--)
    {
        int a;
        scanf(" %s %d",str,&a);
        if(str[0]=='g')
        {
            int x=query(1,1,n,info[a].ff,info[a].ss);
            printf("%d\n",x);
        }
        else
        {
            update(1,1,n,info[a].ff,info[a].ss);
        }
    }



    return 0;
}

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USACO: Cow Pedigrees

Problem Link : http://train.usaco.org/usacoprob2?a=CU0QaF07dUx&S=nocows

Solution Idea: http://zeffsalgo.blogspot.com/2013/12/usaco-training-problem-cow-pedigrees.html


/*
PROG: nocows
LANG: C++
*/
#include <bits/stdc++.h>

#define pii              pair <int,int>
#define pll              pair <long long,long long>
#define sc               scanf
#define pf               printf
#define Pi               2*acos(0.0)
#define ms(a,b)          memset(a, b, sizeof(a))
#define pb(a)            push_back(a)
#define MP               make_pair
#define db               double
#define ll               long long
#define EPS              10E-10
#define ff               first
#define ss               second
#define sqr(x)           (x)*(x)
#define D(x)             cout<<#x " = "<<(x)<<endl
#define VI               vector <int>
#define DBG              pf("Hi\n")
#define MOD              1000000007
#define CIN              ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define SZ(a)            (int)a.size()
#define sf(a)            scanf("%d",&a)
#define sfl(a)           scanf("%lld",&a)
#define sff(a,b)         scanf("%d %d",&a,&b)
#define sffl(a,b)        scanf("%lld %lld",&a,&b)
#define sfff(a,b,c)      scanf("%d %d %d",&a,&b,&c)
#define sfffl(a,b,c)     scanf("%lld %lld %lld",&a,&b,&c)
#define stlloop(v)       for(__typeof(v.begin()) it=v.begin();it!=v.end();it++)
#define loop(i,n)        for(int i=0;i<n;i++)
#define loop1(i,n)       for(int i=1;i<=n;i++)
#define REP(i,a,b)       for(int i=a;i<b;i++)
#define RREP(i,a,b)      for(int i=a;i>=b;i--)
#define TEST_CASE(t)     for(int z=1;z<=t;z++)
#define PRINT_CASE       printf("Case %d: ",z)
#define LINE_PRINT_CASE  printf("Case %d:\n",z)
#define CASE_PRINT       cout<<"Case "<<z<<": "
#define all(a)           a.begin(),a.end()
#define intlim           2147483648
#define infinity         (1<<28)
#define ull              unsigned long long
#define gcd(a, b)        __gcd(a, b)
#define lcm(a, b)        ((a)*((b)/gcd(a,b)))

using namespace std;


/*----------------------Graph Moves----------------*/
//const int fx[]={+1,-1,+0,+0};
//const int fy[]={+0,+0,+1,-1};
//const int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const int fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const int fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move
/*------------------------------------------------*/

/*-----------------------Bitmask------------------*/
//int Set(int N,int pos){return N=N | (1<<pos);}
//int reset(int N,int pos){return N= N & ~(1<<pos);}
//bool check(int N,int pos){return (bool)(N & (1<<pos));}
/*------------------------------------------------*/

int dp[205][102];

int func(int n, int level)
{
    if(n==0 || level==0) return 0;
    if(n==1) return 1;

    int &ret=dp[n][level];
    if(ret!=-1) return ret;

    int ans=0;

    for(int i=1;i<n-1;i++)
    {
        ans+=(func(i,level-1)*func(n-i-1,level-1))%9901;
        ans%=9901;
    }
    return ret=ans;
}


int main()
{    
    freopen("nocows.in","r",stdin);
    freopen("nocows.out","w",stdout);

    int n,k;
    sff(n,k);
    ms(dp,-1);
    printf("%d\n",(9901+func(n,k)-func(n,k-1))%9901);
    return 0;
}


UVa 438 – The Circumference of the Circle

Problem Link : http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=24&page=show_problem&problem=379


#include <bits/stdc++.h>

#define pii              pair <int,int>
#define pll              pair <long long,long long>
#define sc               scanf
#define pf               printf
#define Pi               2*acos(0.0)
#define ms(a,b)          memset(a, b, sizeof(a))
#define pb(a)            push_back(a)
#define MP               make_pair
#define db               double
#define ll               long long
#define EPS              10E-10
#define ff               first
#define ss               second
#define sqr(x)           (x)*(x)
#define D(x)             cout<<#x " = "<<(x)<<endl
#define VI               vector <int>
#define DBG              pf("Hi\n")
#define MOD              1000000007
#define CIN              ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define SZ(a)            (int)a.size()
#define sf(a)            scanf("%d",&a)
#define sfl(a)           scanf("%lld",&a)
#define sff(a,b)         scanf("%d %d",&a,&b)
#define sffl(a,b)        scanf("%lld %lld",&a,&b)
#define sfff(a,b,c)      scanf("%d %d %d",&a,&b,&c)
#define sfffl(a,b,c)     scanf("%lld %lld %lld",&a,&b,&c)
#define stlloop(v)       for(__typeof(v.begin()) it=v.begin();it!=v.end();it++)
#define loop(i,n)        for(int i=0;i<n;i++)
#define loop1(i,n)       for(int i=1;i<=n;i++)
#define REP(i,a,b)       for(int i=a;i<b;i++)
#define RREP(i,a,b)      for(int i=a;i>=b;i--)
#define TEST_CASE(t)     for(int z=1;z<=t;z++)
#define PRINT_CASE       printf("Case %d: ",z)
#define LINE_PRINT_CASE  printf("Case %d:\n",z)
#define CASE_PRINT       cout<<"Case "<<z<<": "
#define all(a)           a.begin(),a.end()
#define intlim           2147483648
#define infinity         (1<<28)
#define ull              unsigned long long
#define gcd(a, b)        __gcd(a, b)
#define lcm(a, b)        ((a)*((b)/gcd(a,b)))

using namespace std;


/*----------------------Graph Moves----------------*/
//const int fx[]={+1,-1,+0,+0};
//const int fy[]={+0,+0,+1,-1};
//const int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const int fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const int fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move
/*------------------------------------------------*/

/*-----------------------Bitmask------------------*/
//int Set(int N,int pos){return N=N | (1<<pos);}
//int reset(int N,int pos){return N= N & ~(1<<pos);}
//bool check(int N,int pos){return (bool)(N & (1<<pos));}
/*------------------------------------------------*/

double dist(double x1, double y1, double x2, double y2)
{
    return sqrt(sqr(x1-x2)+sqr(y1-y2));
}

int main()
{

    ///freopen("in.txt","r",stdin);
    ///freopen("out.txt","w",stdout);


    double x1,y1,x2,y2,x3,y3;
    while(cin>>x1>>y1>>x2>>y2>>x3>>y3)
    {
        double a,b,c;

        //calculating the three side of the triangle

        a=dist(x1,y1,x2,y2);
        b=dist(x2,y2,x3,y3);
        c=dist(x1,y1,x3,y3);

        // calculating the sub perimeter

        double s=(a+b+c)/2.0;

        // calculating the area of the triangle.

        double area=sqrt(s*(s-a)*(s-b)*(s-c));

        // calculating radius using formula area= (a*b*c)/(2*R) ; here R = diameter

        double r=(a*b*c)/(4.0*area);

        cout<<setprecision(2)<<fixed<<Pi*2.0*r<<endl;

    }

    return 0;
}


Light OJ : 1296 – Again Stone Game

Problem Link : http://lightoj.com:81/volume/problem/1296

Solution Idea: Just Find the pattern for smaller input and get AC 😛



#include <bits/stdc++.h>

#define pii              pair <int,int>
#define pll              pair <long long,long long>
#define sc               scanf
#define pf               printf
#define Pi               2*acos(0.0)
#define ms(a,b)          memset(a, b, sizeof(a))
#define pb(a)            push_back(a)
#define MP               make_pair
#define db               double
#define ll               long long
#define EPS              10E-10
#define ff               first
#define ss               second
#define sqr(x)           (x)*(x)
#define D(x)             cout<<#x " = "<<(x)<<endl
#define VI               vector <int>
#define DBG              pf("Hi\n")
#define MOD              1000000007
#define CIN              ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define SZ(a)            (int)a.size()
#define sf(a)            scanf("%d",&a)
#define sfl(a)           scanf("%lld",&a)
#define sff(a,b)         scanf("%d %d",&a,&b)
#define sffl(a,b)        scanf("%lld %lld",&a,&b)
#define sfff(a,b,c)      scanf("%d %d %d",&a,&b,&c)
#define sfffl(a,b,c)     scanf("%lld %lld %lld",&a,&b,&c)
#define stlloop(v)       for(__typeof(v.begin()) it=v.begin();it!=v.end();it++)
#define loop(i,n)        for(int i=0;i<n;i++)
#define loop1(i,n)       for(int i=1;i<=n;i++)
#define REP(i,a,b)       for(int i=a;i<b;i++)
#define RREP(i,a,b)      for(int i=a;i>=b;i--)
#define TEST_CASE(t)     for(int z=1;z<=t;z++)
#define PRINT_CASE       printf("Case %d: ",z)
#define LINE_PRINT_CASE  printf("Case %d:\n",z)
#define CASE_PRINT       cout<<"Case "<<z<<": "
#define all(a)           a.begin(),a.end()
#define intlim           2147483648
#define infinity         (1<<28)
#define ull              unsigned long long
#define gcd(a, b)        __gcd(a, b)
#define lcm(a, b)        ((a)*((b)/gcd(a,b)))

using namespace std;


/*----------------------Graph Moves----------------*/
//const int fx[]={+1,-1,+0,+0};
//const int fy[]={+0,+0,+1,-1};
//const int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const int fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const int fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move
/*------------------------------------------------*/

/*-----------------------Bitmask------------------*/
//int Set(int N,int pos){return N=N | (1<<pos);}
//int reset(int N,int pos){return N= N & ~(1<<pos);}
//bool check(int N,int pos){return (bool)(N & (1<<pos));}
/*------------------------------------------------*/


int main()
{

    ///freopen("in.txt","r",stdin);
    ///freopen("out.txt","w",stdout);

    int t;
    sf(t);
    TEST_CASE(t)
    {
        int n;
        sf(n);

        int ans=0;

        for(int i=0;i<n;i++)
        {
            int a;
            sf(a);
            while(a%2)
            {
                a/=2;
            }
            ans^=a/2;
        }

        PRINT_CASE;
        if(ans)
            pf("Alice\n");
        else
            pf("Bob\n");

    }

    return 0;
}


Light OJ: 1199 – Partitioning Game

Problem Link : http://lightoj.com:81/volume/problem/1199


#include <bits/stdc++.h>

#define pii              pair <int,int>
#define pll              pair <long long,long long>
#define sc               scanf
#define pf               printf
#define Pi               2*acos(0.0)
#define ms(a,b)          memset(a, b, sizeof(a))
#define pb(a)            push_back(a)
#define MP               make_pair
#define db               double
#define ll               long long
#define EPS              10E-10
#define ff               first
#define ss               second
#define sqr(x)           (x)*(x)
#define D(x)             cout<<#x " = "<<(x)<<endl
#define VI               vector <int>
#define DBG              pf("Hi\n")
#define MOD              1000000007
#define CIN              ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define SZ(a)            (int)a.size()
#define sf(a)            scanf("%d",&a)
#define sfl(a)           scanf("%lld",&a)
#define sff(a,b)         scanf("%d %d",&a,&b)
#define sffl(a,b)        scanf("%lld %lld",&a,&b)
#define sfff(a,b,c)      scanf("%d %d %d",&a,&b,&c)
#define sfffl(a,b,c)     scanf("%lld %lld %lld",&a,&b,&c)
#define stlloop(v)       for(__typeof(v.begin()) it=v.begin();it!=v.end();it++)
#define loop(i,n)        for(int i=0;i<n;i++)
#define loop1(i,n)       for(int i=1;i<=n;i++)
#define REP(i,a,b)       for(int i=a;i<b;i++)
#define RREP(i,a,b)      for(int i=a;i>=b;i--)
#define TEST_CASE(t)     for(int z=1;z<=t;z++)
#define PRINT_CASE       printf("Case %d: ",z)
#define LINE_PRINT_CASE  printf("Case %d:\n",z)
#define CASE_PRINT       cout<<"Case "<<z<<": "
#define all(a)           a.begin(),a.end()
#define intlim           2147483648
#define infinity         (1<<28)
#define ull              unsigned long long
#define gcd(a, b)        __gcd(a, b)
#define lcm(a, b)        ((a)*((b)/gcd(a,b)))

using namespace std;


/*----------------------Graph Moves----------------*/
//const int fx[]={+1,-1,+0,+0};
//const int fy[]={+0,+0,+1,-1};
//const int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const int fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const int fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move
/*------------------------------------------------*/

/*-----------------------Bitmask------------------*/
//int Set(int N,int pos){return N=N | (1<<pos);}
//int reset(int N,int pos){return N= N & ~(1<<pos);}
//bool check(int N,int pos){return (bool)(N & (1<<pos));}
/*------------------------------------------------*/

int dp[10005];

int func(int n)
{
    if(n==1 || n==2) return 0;

    if(dp[n]!=-1) return dp[n];

    set<int>st;

    int mid=n/2;
    if(n%2==0) mid--;

    for(int i=1;i<=mid;i++)
    {
        st.insert(func(i)^func(n-i));
    }

    int ret=0;
    while(st.find(ret)!=st.end()) ret++;
    return dp[n]=ret;
}

int main()
{

    ///freopen("in.txt","r",stdin);
    ///freopen("out.txt","w",stdout);

    ms(dp,-1);

    int t;
    sf(t);
    TEST_CASE(t)
    {
        int n;
        sf(n);

        int ans=0;

        for(int i=0;i<n;i++)
        {
            int a;
            sf(a);
            ans^=func(a);
        }

        PRINT_CASE;

        if(ans)
            pf("Alice\n");
        else
            pf("Bob\n");

    }

    return 0;
}


UVa : 10938 – Flea circus

Problem Link : http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=24&page=show_problem&problem=1879

Solution Idea: Find the LCA. Then find the middle node and middle+1 node on the path connection two nodes which are given in the query. Here I use an extra DFS to find the path on a reverse graph g2.


#include <bits/stdc++.h>

#define pii              pair <int,int>
#define pll              pair <long long,long long>
#define sc               scanf
#define pf               printf
#define Pi               2*acos(0.0)
#define ms(a,b)          memset(a, b, sizeof(a))
#define pb(a)            push_back(a)
#define MP               make_pair
#define db               double
#define ll               long long
#define EPS              10E-10
#define ff               first
#define ss               second
#define sqr(x)           (x)*(x)
#define D(x)             cout<<#x " = "<<(x)<<endl
#define VI               vector <int>
#define DBG              pf("Hi\n")
#define MOD              1000000007
#define CIN              ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define SZ(a)            (int)a.size()
#define sf(a)            scanf("%d",&a)
#define sfl(a)           scanf("%lld",&a)
#define sff(a,b)         scanf("%d %d",&a,&b)
#define sffl(a,b)        scanf("%lld %lld",&a,&b)
#define sfff(a,b,c)      scanf("%d %d %d",&a,&b,&c)
#define sfffl(a,b,c)     scanf("%lld %lld %lld",&a,&b,&c)
#define stlloop(v)       for(__typeof(v.begin()) it=v.begin();it!=v.end();it++)
#define loop(i,n)        for(int i=0;i<n;i++)
#define loop1(i,n)       for(int i=1;i<=n;i++)
#define REP(i,a,b)       for(int i=a;i<b;i++)
#define RREP(i,a,b)      for(int i=a;i>=b;i--)
#define TEST_CASE(t)     for(int z=1;z<=t;z++)
#define PRINT_CASE       printf("Case %d: ",z)
#define LINE_PRINT_CASE  printf("Case %d:\n",z)
#define CASE_PRINT       cout<<"Case "<<z<<": "
#define all(a)           a.begin(),a.end()
#define intlim           2147483648
#define infinity         (1<<28)
#define ull              unsigned long long
#define gcd(a, b)        __gcd(a, b)
#define lcm(a, b)        ((a)*((b)/gcd(a,b)))

using namespace std;


/*----------------------Graph Moves----------------*/
//const int fx[]={+1,-1,+0,+0};
//const int fy[]={+0,+0,+1,-1};
//const int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const int fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const int fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move
/*------------------------------------------------*/

/*-----------------------Bitmask------------------*/
//int Set(int N,int pos){return N=N | (1<<pos);}
//int reset(int N,int pos){return N= N & ~(1<<pos);}
//bool check(int N,int pos){return (bool)(N & (1<<pos));}
/*------------------------------------------------*/

#define mx 5005
int n,q;

vector<int>g1[mx],g2[mx];

int sparse_par[mx][14],sparse_dis[mx][14];

int level[mx],par[mx];

void dfs(int u, int cnt, int from)
{
    par[u]=from;
    level[u]=cnt;
    g2[u].pb(from);

    for(int i=0;i<SZ(g1[u]);i++)
    {
        int v=g1[u][i];
        if(v!=from)
        {
            dfs(v,cnt+1,u);
        }
    }
}


void build_talbe()
{
    for(int i=1;i<=n;i++)
    {
        sparse_par[i][0]=par[i];
        sparse_dis[i][0]=1;
    }
    sparse_dis[1][0]=0;

    for(int j=1; 1<<j<=n;j++)
    {
        for(int i=1;i<=n;i++)
        {
            sparse_par[i][j]=sparse_par[sparse_par[i][j-1]][j-1];
            sparse_dis[i][j]=sparse_dis[i][j-1]+sparse_dis[sparse_par[i][j-1]][j-1];
        }
    }
}

int LCA;

int query(int p, int q)
{
    if(level[p]<=level[q]) swap(p,q);

    int log=log2(level[p]);

    int ret=0;

    for(int i=log;i>=0;i--)
    {
        if(level[p]-(1<<i)>=level[q])
        {
            ret+=sparse_dis[p][i];
            p=sparse_par[p][i];
        }
    }


    if(p==q){LCA=p; return ret;}

    for(int i=log;i>=0;i--)
    {
        if(sparse_par[p][i]!=sparse_par[q][i])
        {
            ret+=sparse_dis[p][i];
            ret+=sparse_dis[q][i];
            p=sparse_par[p][i];
            q=sparse_par[q][i];
        }
    }
    ret+=2;
    LCA=par[p];
    return ret;
}


vector<int>temp;

int dfs1(int u, int cnt)
{
    if(u==LCA) return u;
    temp.pb(u);
    if(cnt==0) return u;
    for(int i=0;i<SZ(g2[u]);i++)
        return dfs1(g2[u][i],cnt-1);
}

int main()
{

//    freopen("in.txt","r",stdin);
//    freopen("out.txt","w",stdout);

    while(sf(n) && n)
    {
        loop(i,n-1)
        {
            int a,b;
            sff(a,b);
            g1[a].pb(b);
            g1[b].pb(a);
        }

        dfs(1,0,1);

        build_talbe();

        sf(q);

        while(q--)
        {
            int a,b;
            sff(a,b);

            int dis=query(a,b)+1;

            if(dis%2==0)
            {
                temp.clear();
                dfs1(a,n);
                temp.pb(LCA);
                int x=SZ(temp);
                dfs1(b,n);
                reverse(temp.begin()+x,temp.end());
                int aa=temp[(dis/2)-1];
                int bb=temp[dis/2];
                pf("The fleas jump forever between %d and %d.\n",min(aa,bb),max(aa,bb));

            }
            else
            {
                int p;
                if(level[a]>level[b])
                    p=a;
                else
                    p=b;
                pf("The fleas meet at %d.\n",dfs1(p,dis/2));
            }
        }

        for(int i=0;i<=n;i++)
        {
            g1[i].clear();
            g2[i].clear();
        }

    }


    return 0;
}


UVa : 12238 – Ants Colony

Problem Link : http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=24&page=show_problem&problem=3390


#include <bits/stdc++.h>

#define pii              pair <int,int>
#define pll              pair <long long,long long>
#define sc               scanf
#define pf               printf
#define Pi               2*acos(0.0)
#define ms(a,b)          memset(a, b, sizeof(a))
#define pb(a)            push_back(a)
#define MP               make_pair
#define db               double
#define ll               long long
#define EPS              10E-10
#define ff               first
#define ss               second
#define sqr(x)           (x)*(x)
#define D(x)             cout<<#x " = "<<(x)<<endl
#define VI               vector <int>
#define DBG              pf("Hi\n")
#define MOD              1000000007
#define CIN              ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define SZ(a)            (int)a.size()
#define sf(a)            scanf("%d",&a)
#define sfl(a)           scanf("%lld",&a)
#define sff(a,b)         scanf("%d %d",&a,&b)
#define sffl(a,b)        scanf("%lld %lld",&a,&b)
#define sfff(a,b,c)      scanf("%d %d %d",&a,&b,&c)
#define sfffl(a,b,c)     scanf("%lld %lld %lld",&a,&b,&c)
#define stlloop(v)       for(__typeof(v.begin()) it=v.begin();it!=v.end();it++)
#define loop(i,n)        for(int i=0;i<n;i++)
#define loop1(i,n)       for(int i=1;i<=n;i++)
#define REP(i,a,b)       for(int i=a;i<b;i++)
#define RREP(i,a,b)      for(int i=a;i>=b;i--)
#define TEST_CASE(t)     for(int z=1;z<=t;z++)
#define PRINT_CASE       printf("Case %d: ",z)
#define LINE_PRINT_CASE  printf("Case %d:\n",z)
#define CASE_PRINT       cout<<"Case "<<z<<": "
#define all(a)           a.begin(),a.end()
#define intlim           2147483648
#define infinity         (1<<28)
#define ull              unsigned long long
#define gcd(a, b)        __gcd(a, b)
#define lcm(a, b)        ((a)*((b)/gcd(a,b)))

using namespace std;


/*----------------------Graph Moves----------------*/
//const int fx[]={+1,-1,+0,+0};
//const int fy[]={+0,+0,+1,-1};
//const int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const int fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const int fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move
/*------------------------------------------------*/

/*-----------------------Bitmask------------------*/
//int Set(int N,int pos){return N=N | (1<<pos);}
//int reset(int N,int pos){return N= N & ~(1<<pos);}
//bool check(int N,int pos){return (bool)(N & (1<<pos));}
/*------------------------------------------------*/

#define mx 100005

int n;
int level[mx],par[mx],dis[mx];

vector<int>g[mx],cost[mx];

ll sparse_par[mx][20],sparse_sum[mx][20];

void dfs(int u, int cnt, int from)
{
    par[u]=from;
    level[u]=cnt;

    for(int i=0;i<SZ(g[u]);i++)
    {
        int v=g[u][i];

        if(v!=from)
        {
            dis[v]=cost[u][i];
            dfs(v,cnt+1,u);
        }

    }

}


void build_table()
{
    for(int i=0;i<n;i++)
    {
        sparse_par[i][0]=par[i];
        sparse_sum[i][0]=dis[i];
    }

    for(int j=1;1<<j<n;j++)
    {
        for(int i=0;i<n;i++)
        {
            sparse_par[i][j]=sparse_par[sparse_par[i][j-1]][j-1];
            sparse_sum[i][j]=sparse_sum[i][j-1]+sparse_sum[sparse_par[i][j-1]][j-1];
//            D(i);
//            D(j);
//            D(sparse_par[i][j]);
//            D(sparse_sum[i][j]);
        }
    }

}


ll query(int p, int q)
{
    ll ret=0;
    if(level[p]<=level[q]) swap(p,q);

    int log=log2(level[p]);

    for(int i=log;i>=0;i--)
    {
        if(level[p]-(1<<i)>=level[q])
        {
            ret+=sparse_sum[p][i];
            p=sparse_par[p][i];
        }
    }

    if(p==q) return ret;

    for(int i=log;i>=0;i--)
    {
        if(sparse_par[p][i]!=sparse_par[q][i])
        {
            ret+=sparse_sum[p][i];
            ret+=sparse_sum[q][i];
            p=sparse_par[p][i];
            q=sparse_par[q][i];
        }
    }


    ret+=dis[p];
    ret+=dis[q];
    return ret;

}

int main()
{

//    freopen("in.txt","r",stdin);
    ///freopen("out.txt","w",stdout);

    while(sf(n) && n)
    {
        for(int i=1;i<n;i++)
        {
            int a,b;
            sff(a,b);
            g[i].pb(a);
            g[a].pb(i);
            cost[a].pb(b);
            cost[i].pb(b);
        }

        dis[0]=0;

        dfs(0,0,0);

        build_table();

        int q;
        sf(q);

        bool test=1;

        while(q--)
        {
            int a,b;
            sff(a,b);

            ll ans=query(a,b);

            if(test)
            {
                printf("%lld",ans);
                test=0;
            }
            else
            {
                printf(" %lld",ans);
            }

        }

        printf("\n");

        for(int i=0;i<=n;i++)
        {
            g[i].clear();
            cost[i].clear();
        }

    }

    return 0;
}