UVa 10102 - The path in the colored field Solution

#include<iostream>
#include<list>
#include<string>
#include<cstring>
#include<sstream>
#include<cctype>
#include<string.h>
#include<algorithm>
#include<cmath>
#include<stack>
#include<fstream>
#include<cstdlib>
#include<vector>
#include<map>
#include<set>
#include<utility>
#include<iomanip>
#include<queue>

using namespace std;

#define INF (1<<29)
#define SET(a) memset(a,-1,sizeof(a))
#define ALL(a) a.begin(),a.end()
#define CLR(a) memset(a,0,sizeof(a))
#define FILL(a,v) memset(a,v,sizeof(a))
#define PB push_back
#define FOR(i,n) for(int i = 0;i<n;i++)
#define PI acos(-1.0)
#define EPS 1e-9
#define MP(a,b) make_pair(a,b)
#define min3(a,b,c) min(a,min(b,c))
#define max3(a,b,c) max(a,max(b,c))
#define READ(f) freopen(f, "r", stdin)
#define WRITE(f) freopen(f, "w", stdout)
#define LL long long
#define MX 100000
#define MOD 1000000007

char grid[1000][1000];
int m;

int min_dist(int x,int y)
{
    int mn=1000;
    for(int i=0;i<m;i++)
        for(int j=0;j<m;j++)
            if(grid[i][j]=='3')
            {
                int tmp=abs(x-i)+abs(y-j);
                mn=min(mn,tmp);
            }
    return mn;
}

main()
{
    while(cin>>m)
    {
        CLR(grid);
        for(int i=0;i<m;i++)
            for(int j=0;j<m;j++)
                cin>>grid[i][j];

        int mx=0;
        for(int i=0;i<m;i++)
            for(int j=0;j<m;j++)
                if(grid[i][j]=='1')
                {
                int tmp=min_dist(i,j);
                mx=max(mx,tmp);
                }
    cout<<mx<<endl;
    }
}