POJ1734Sightseeing trip(最小环)

题目链接。

分析：

请参考本文章。

AC代码（输出的顺序不唯一）：

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

#define MAXN 102

#define min(x, y) ((x)<(y)?(x):(y))

const int INF = (1<<24);

int G[MAXN][MAXN], dis[MAXN][MAXN], pre[MAXN][MAXN], path[MAXN];
int n, m, min_cost, cnt;

void floyd(){
    int i, j, k, p;
    for(i=0; i<n; i++){
        for(j=0; j<n; j++){
            dis[i][j] = G[i][j];
        }
        dis[i][i] = 0;
    }
    for(k=0; k<n; k++){
        for(i=0; i<k; i++){
            for(j=i+1; j<k; j++){
                if(min_cost > dis[i][j]+G[i][k]+G[k][j]){
                    min_cost = dis[i][j]+G[i][k]+G[k][j];
                    cnt = 0;
                    p = j;
                    while(p != i){
                        path[cnt++] = p;
                        p = pre[i][p];
                    }
                    path[cnt++] = i;
                    path[cnt++] = k;
                }
            }
        }

        for(i=0; i<n; i++){
            for(j=0; j<n; j++){
                if(dis[i][j] > dis[i][k]+dis[k][j]){
                    dis[i][j] = dis[i][k]+dis[k][j];
                    pre[i][j] = pre[k][j];
                }
            }
        }
    }
}

int main(){
    int i, u, v, w, j;

    while(scanf("%d %d", &n, &m) == 2){
        min_cost = INF;
        for(i=0; i<n; i++){
            for(j=0; j<n; j++){
                G[i][j] = INF;
                pre[i][j] = i;
            }
        }

        for(i=0; i<m; i++){
            scanf("%d %d %d", &u, &v, &w);
            u--; v--;
            if(G[u][u]>w){
                G[u][v] = G[v][u] = w;
            }
        }

        floyd();

        if(min_cost == INF) printf("No solution.\n");
        else{
            for(i=0; i<cnt; i++){
                if(i != cnt-1) printf("%d ", path[i]+1);
                else printf("%d\n", path[i]+1);
            }
        }
    }

    return 0;
}