lightoj 1019

裸的最短路 dijkstra

#include<cstdio>
#include<string>
#include<cstring>
#include<iostream>
using namespace std;
const int MAXN = 101;
const int INF = 0x3f3f3f3f;
int dist[MAXN], vis[MAXN], mat[MAXN][MAXN];
int main(){
    int t, u, v, w, n, m, CASE(0);
    scanf("%d", &t);
    while(t--){
        scanf("%d%d", &n, &m);
        memset(mat, 0x3f, sizeof mat);
        memset(dist, 0x3f, sizeof dist);
        for(int i = 0;i < m;i ++){
            scanf("%d%d%d", &u, &v, &w);
            mat[u][v] = mat[v][u] = min(mat[u][v], w);
        }
        dist[1] = 0;
        memset(vis, 0, sizeof vis);
        vis[1] = 1;
        for(int i = 1;i <= n;i ++) if(mat[1][i] != INF) dist[i] = mat[1][i];
        for(int i = 0;i < n;i ++){
            int minn(INF), k(-1);
            for(int j = 1;j <= n;j ++){
                if(!vis[j] && minn > dist[j]){
                    minn = dist[j];
                    k = j;
                }

            }
            if(k == -1) break;
            vis[k] = 1;
            for(int j = 1;j <= n;j ++){
                if(!vis[j] && mat[k][j] + dist[k] < dist[j]) dist[j] = mat[k][j] + dist[k];
            }
        }
        printf("Case %d: ", ++CASE);
        if(dist[n] == INF) printf("Impossible
");
        else printf("%d
", dist[n]);
    }
    return 0;
}