HDU 1874

HDU 1874

Dijkstra

注意初始化

#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
const int N = 1e3 + 10,INF = 0x3f3f3f3f;
int n,m,dist[N],g[N][N];
bool st[N];
void dij(int x) {
    memset(dist,0x3f,sizeof dist);
    memset(st,0,sizeof st);
    dist[x] = 0;
    for(int i = 0;i < n; ++i) {
        int t = -1;
        for(int j = 0;j < n; ++j) {
            if(!st[j] && (t == -1 || dist[t] > dist[j])) t = j;
        }
        st[t] = 1;
        for(int j = 0;j < n; ++j) {
            dist[j] = min(dist[j],dist[t] + g[t][j]);
        }
    }
}
int main() {
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    while(cin >> n >> m) {
        int a,b,c,starti,endi;
        memset(g,0x3f,sizeof g);
        for(int i = 0;i < m; ++i) {
            cin >> a >> b >> c;
            g[a][b] = g[b][a] = min(g[a][b],c);
        }
        cin >> starti >> endi;
        dij(starti);
        if(dist[endi] == INF) cout << "-1";
        else cout << dist[endi];
        cout << endl;
    }
    return 0;
}