poj 1734 Sightseeing trip_ 最小环记录路径

题意：求最出小环，输出路径

#include <iostream>
#include<cstdio>
using namespace std;
#define N 110
#define INF 0xffffff
int map[N][N],n,m,dist[N][N],pre[N][N],path[N];
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
void floyd(){
	int i,j,k,ans=INF,num,p;
	for(i=0;i<=n;i++)
		for(j=0;j<=n;j++)
			dist[i][j]=map[i][j];
	for(k=1;k<=n;k++){
		for(i=1;i<k;i++)
			for(j=i+1;j<k;j++){
				int tmp=dist[i][j]+map[i][k]+map[k][j];
				if(tmp<ans){	
					ans=dist[i][j]+map[i][k]+map[k][j];
					p=j;
					num=0;
					while(p!=i){
						path[num++]=p;
						p=pre[i][p];
					}
					path[num++]=i;
					path[num++]=k;
				}
			}
				
		for(i=1;i<=n;i++)
			for(j=1;j<=n;j++){
				int tmp=dist[i][k]+dist[k][j];
				if(dist[i][j]>dist[i][k]+dist[k][j]){
					dist[i][j]=dist[i][k]+dist[k][j];
					pre[i][j]=pre[k][j];
				}
			}
	}
	if(ans==INF)
		printf("No solution.\n");
	else{
		printf("%d",path[0]);
		for(i=1;i<num;i++)
			printf(" %d",path[i]);
		puts("");
	}	
}
int main(int argc, char** argv) {
	int i,j,a,b,d;
//	freopen("in.txt","r",stdin);
	while(scanf("%d%d",&n,&m)!=EOF){
		for(i=1;i<=n;i++)
			for(j=1;j<=n;j++){
				map[i][j]=INF;
				pre[i][j]=i;
			}
		for(i=0;i<m;i++){
			scanf("%d%d%d",&a,&b,&d);
			if(map[a][b]>d)
				map[a][b]=map[b][a]=d;
		}
		floyd();
	}
	return 0;
}