hdu 1599 find the mincost route floyd求最小环

#include<stdio.h>
#include<string.h>
#include<algorithm>

using namespace std;

const int inf = 1 << 28;
const int N = 105;

int a

;
int dis

;
int n, m;
int ans;

void init()
{
	for( int i = 1; i <= n; i++ )
	{
		for( int j = 1; j <= n; j++ )
		{
			dis[i][j] = dis[j][i] = a[i][j] = (i == j? 0: inf);
		}
	}
}

void floyd()
{
	ans = inf;
	for( int k = 1; k <= n; k ++)
	{
		for( int i = 1; i < k; i++ )
		{
			for( int j = 1+i; j < k; j++ )
				ans = min(ans, a[k][i] + dis[i][j] + a[j][k]);
		}
		for( int i = 1; i <= n; i++ )
		{
			for( int j = 1; j <= n; j++ )
			{
				dis[i][j] = min(dis[i][j], dis[i][k] + dis[k][j]);
			}
		}
	}
}

int main()
{
	while(~scanf("%d%d", &n, &m))
	{
		init();
		int u, v, w;
		for( int i = 1; i <= m; i++ )
		{
			scanf("%d%d%d", &u, &v, &w);
			dis[u][v] = dis[v][u] = a[u][v] = a[v][u] = min(w, a[u][v]);
		}
		floyd();
		if( ans >= inf )
			puts("It's impossible.");
		else
			printf("%d\n", ans);
	}
	return 0;
}