Light OJ 1066 – Gathering Food

Problem Link : http://www.lightoj.com/volume_showproblem.php?problem=1066


/*
         +-+ +-+ +-+
         |R| |.| |S|
         +-+ +-+ +-+
 */

#include <bits/stdc++.h>

#define pii             pair <int,int>
#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             100007
#define MAX             10000
#define CIN             ios_base::sync_with_stdio(0); cin.tie(0)
#define SZ(a)           (int)a.size()
#define sf(a)           scanf("%d",&a)
#define sff(a,b)        scanf("%d%d",&a,&b)
#define sfff(a,b,c)     scanf("%d%d%d",&a,&b,&c)
#define loop(i,n)       for(int i=0;i<n;i++)
#define REP(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 all(a)          a.begin(),a.end()
#define intlim          2147483648
#define inf             1000000
#define ull             unsigned long long


using namespace std;

const int fx[]= {+1,-1,+0,+0};
const int fy[]= {+0,+0,+1,-1};

char ara[12][12],ch;
int cnt,n;
bool visited[12][12];
int d[12][12];
map<char,pii> mp;

bool test(pii temp)
{
    if(temp.ff<0 || temp.ff>=n || temp.ss<0 || temp.ss>=n || visited[temp.ff][temp.ss]|| ara[temp.ff][temp.ss]=='#')
        return 0;
    if(ara[temp.ff][temp.ss]>='A' && ara[temp.ff][temp.ss]<='Z')
    {
        if(ara[temp.ff][temp.ss]>ch)
            return 0;
    }
    return 1;
}

int bfs(pii src, pii dst)
{
    pii u=src;
    visited[u.ff][u.ss]=1;
    d[u.ff][u.ss]=0;
    queue<pii>Q;
    Q.push(u);
    while(!Q.empty())
    {
        u=Q.front();
        Q.pop();
        if(u==dst) return d[u.ff][u.ss];
        pii v;
        for(int i=0; i<4; i++)
        {
            v.ff=u.ff+fx[i];
            v.ss=u.ss+fy[i];
            if(test(v))
            {
                visited[v.ff][v.ss]=1;
                d[v.ff][v.ss]=d[u.ff][u.ss]+1;
                Q.push(v);
            }
        }
    }
    return -1;
}

int main()
{
    ///freopen("in.txt","r",stdin);
    ///freopen("out.txt","w",stdout);
    int t;
    sf(t);
    TEST_CASE(t)
    {
        sf(n);
        cnt=0;
        loop(i,n)
        loop(j,n)
        {
            cin>>ara[i][j];
            if(ara[i][j]>='A' && ara[i][j]<='Z')
            {
                cnt++;
                mp[ara[i][j]]=MP(i,j);
            }
        }
        int ans=0;
        bool ispossible=1;
        for(int i=0; i<cnt-1; i++)
        {
            int tmp=0;
            ch='A'+i+1;
            tmp=bfs(mp['A'+i],mp['A'+i+1]);
            ms(d,0);
            ms(visited,0);
            if(tmp==-1)
            {
                ispossible=0;
                break;
            }
            else
                ans+=tmp;

        }
        PRINT_CASE;
        if(ispossible)
            pf("%d\n",ans);
        else
            pf("Impossible\n");
        mp.clear();
    }
    return 0;
}

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