hdu 1869赤裸裸的最短路

/*

 * hdu1869/win.cpp

 * Created on: 2012-7-31

 * Author    : ben

 */

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <cmath>

#include <ctime>

#include <iostream>

#include <algorithm>

#include <queue>

#include <set>

#include <stack>

#include <string>

#include <vector>

#include <deque>

#include <list>

#include <functional>

#include <numeric>

#include <cctype>

using namespace std;



const int SIZE = 105;

const int MAX = 0x7fffffff;

int mymap[SIZE][SIZE], N;

void init() {

    int i, j;

    for (i = 0; i < N; i++) {

        for (j = 0; j < N; j++) {

            mymap[i][j] = MAX;

        }

    }

}

void Floyd() {

    int i, j, k;

    for (k = 0; k < N; k++) {

        for (i = 0; i < N; i++) {

            for (j = 0; j < N; j++) {

                if(mymap[i][k] < mymap[i][j] - mymap[k][j]) {

                    mymap[i][j] = mymap[i][k] + mymap[k][j];

                }

            }

        }

    }

}

int main() {

#ifndef ONLINE_JUDGE

    freopen("data.in", "r", stdin);

#endif

    int M, a, b;

    while(scanf("%d%d", &N, &M) == 2) {

        init();

        for(int i = 0; i < M; i++) {

            scanf("%d%d", &a, &b);

            mymap[a][b] = mymap[b][a] = 1;

        }

        Floyd();

        bool flag = true;

        for(int i = 0; i < N; i++) {

            for(int j = i + 1; j < N; j++) {

                if(mymap[i][j] > 7) {

                    flag = false;

                }

            }

        }

        puts(flag ? "Yes" : "No");

    }

    return 0;

}