40 lines
834 B
C++
40 lines
834 B
C++
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#include <bits/stdc++.h>
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using namespace std;
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const int INF = 0x3f3f3f3f;
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const int N = 2510; //结点数
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const int M = 6200 * 2 + 10; //边数
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struct Edge {
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int a, b, c;
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} edges[M];
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int n, m; // n个结点，m条边
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int s, t; //起点，终点
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int d[N]; //距离数组
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void bellman_ford(int start) {
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memset(d, 0x3f, sizeof d);
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d[start] = 0;
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int T = n - 1;
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while (T--) {
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for (int i = 0; i < 2 * m; i++) {
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auto j = edges[i];
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d[j.b] = min(d[j.b], d[j.a] + j.c);
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}
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}
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}
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int main() {
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cin >> n >> m >> s >> t;
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for (int i = 0; i < m; i++) {
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int a, b, c;
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cin >> a >> b >> c;
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edges[i] = {a, b, c}, edges[m + i] = {b, a, c};
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}
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bellman_ford(s);
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cout << d[t] << endl;
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return 0;
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}
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