杭电ACM HDU 1869 六度分离

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <queue>
#include <stack>
#include <vector>
#include <map>
#include <cmath>
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define LL long long
using namespace std;

const int INF=0x3f3f3f3f;
const int MX=100+10;

int n,m,Map[MX][MX];
void init(){
    for (int i=0;i<n;i++)
        for (int j=0;j<n;j++)
            if (i==j) Map[i][j]=0;
            else Map[i][j]=INF;
}
void Floyd(){
    for (int k=0;k<n;k++){
        for (int i=0;i<n;i++)
            for (int j=0;j<n;j++)
                if (Map[i][j]>Map[i][k]+Map[k][j])
                    Map[i][j]=Map[i][k]+Map[k][j];
    }
}
int main(){
    while (~scanf ("%d %d",&n,&m)){
        init();
        while (m--){
            int u,v;
            scanf ("%d %d",&u,&v);
            if (Map[u][v]>1){
                Map[u][v]=1;
                Map[v][u]=1;
            }
        }
        Floyd();
        bool sign=true;
        for (int i=0;i<n&&sign;i++)
            for (int j=i+1;j<n&&sign;j++)
                if (Map[i][j]>7) sign=false;
        printf ("%s\n",sign?"Yes":"No");
    }
    return 0;
}