Floyd最小环Hdu1599

http://acm.hdu.edu.cn/showproblem.php?pid=1599

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <algorithm>

#include <cmath>

#include <stack>

#include <queue>

#include <vector>

#include <map>

#include <string>

#include <iostream>

using namespace std;

const int INF=0xfffffff;

int Min(int a,int b)

{

	return a>b?b:a;

}

int Map[1111][1111];

int dp[1111][1111];

int main()

{

	int n,m;

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

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

	while(scanf("%d%d",&n,&m)!=EOF){

		int ans=INF;

		for(int i=1;i<=n;i++)

			for(int j=1;j<=n;j++)

			Map[i][j]=INF;

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

			int a,b,c;

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

			if(Map[a][b]>c){

				Map[a][b]=Map[b][a]=c;

			}

		}

		for(int i=1;i<=n;i++)

			for(int j=1;j<=n;j++)

			dp[i][j]=Map[i][j];

		for(int k=1;k<=n;k++){

			for(int i=1;i<=n;i++){

				for(int j=1;j<=n;j++)

					ans=Min(ans,dp[i][j]+Map[k][i]+Map[k][j]);

			}

			for(int i=1;i<=n;i++)

			for(int j=1;j<=n;j++){

				if(dp[i][j]>dp[i][k]+dp[k][j])

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

			}

		}

		if(ans==INF)

			printf("It's impossible.\n");

		else

			printf("%d\n",ans);

	}

	return 0;

}