#include <iostream> #include <cstring> using namespace std; const int N = 1000010; int n, m, s, t; bool st[N]; int h[N], e[N], w[N], ne[N], idx; int d[N]; void add(int a, int b, int c) { e[idx] = b, w[idx] = c, ne[idx] = h[a], h[a] = idx ++; } int dijkstra() { memset(d, 0x3f, sizeof d); d[s] = 0; for (int i = 0; i < n; i ++ ) { int t = -1; for (int j = 1; j <= n; j ++ ) if (!st[j] && (t == -1 || d[t] > d[j])) t = j; st[t] = true; for (int j = h[t]; j != -1; j = ne[j]) { int k = e[j]; if (d[k] > d[t] + w[j]) d[k] = d[t] + w[j]; } } return d[t]; } int main() { cin >> n >> m >> s >> t; memset(h, -1, sizeof h); while (m -- ) { int a, b, c; cin >> a >> b >> c; add(a, b, c); add(b, a, c); } cout << dijkstra() << endl; return 0; }帮我将这段代码中的变量a,b,c改为uvw

好的，修改后的代码如下：

#include <iostream>
#include <cstring>
using namespace std;

const int N = 1000010;
int n, m, s, t;
bool st[N];
int h[N], e[N], w[N], ne[N], idx;
int d[N];

void add(int u, int v, int w) {
    e[idx] = v, w[idx] = w, ne[idx] = h[u], h[u] = idx ++;
}

int dijkstra() {
    memset(d, 0x3f, sizeof d);
    d[s] = 0;

    for (int i = 0; i < n; i ++ ) {
        int t = -1;
        for (int j = 1; j <= n; j ++ )
            if (!st[j] && (t == -1 || d[t] > d[j]))
                t = j;

        st[t] = true;

        for (int j = h[t]; j != -1; j = ne[j]) {
            int k = e[j];
            if (d[k] > d[t] + w[j])
                d[k] = d[t] + w[j];
        }
    }

    return d[t];
}

int main() {
    cin >> n >> m >> s >> t;
    memset(h, -1, sizeof h);
    while (m -- ) {
        int u, v, w;
        cin >> u >> v >> w;
        add(u, v, w);
        add(v, u, w);
    }

    cout << dijkstra() << endl;

    return 0;
}