HDU-1874-畅通工程续

这题应该算是最简单的最短路了，没什么好说的。

#include <iostream>
#include <cstring>
using namespace std;
const int INF = 1 << 30;
int n, m, s, e, t;
int d[205], w[205][205];
bool vis[205];

void Dijkstra()
{
    memset(vis, 0, sizeof(vis));
    for (int i = 0; i < n;i++) {
        d[i] = w[s][i];
    }
    vis[s] = 1;
    d[s] = 0;
    for (int i = 1; i < n;i++) {
        int m=INF, k=0;
        for (int j = 0; j < n;j++) {
            if (!vis[j]&&d[j]<m)
                m = d[k = j];
        }
        if (m==INF)
            break;
        vis[k] = 1;
        for (int j = 0; j < n;j++) {
            if (!vis[j]&&d[j]>d[k]+w[k][j])
                d[j] = d[k] + w[k][j];
        }
    }
}

int main()
{
    ios::sync_with_stdio(false);
    while (cin>>n>>m) {
        for (int i = 0; i < n;i++)
            for (int j = 0; j < n;j++)
                w[i][j] = INF;
        for (int i = 0; i < m;i++) {
            cin >> s >> e >> t;
            if (w[s][e]>t)
                w[s][e] = w[e][s] = t;
        }
        cin >> s >> e;
        Dijkstra();
        int ans = d[e] == INF ? -1 : d[e];
        cout << ans << endl;
    }
    return 0;
}