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51 lines
1.2 KiB
51 lines
1.2 KiB
#include <cstdio>
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#include <cstring>
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#include <algorithm>
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#include <iostream>
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using namespace std;
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const int INF = 0x3f3f3f3f;
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const int N = 502;
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int n, m, w;
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int g[N][N];
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// floyd判断是否存在负圈
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bool floyd() {
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for (int k = 1; k <= n; k++)
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for (int i = 1; i <= n; i++)
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if (g[i][k] != INF) { // 优化
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for (int j = 1; j <= n; j++)
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if (g[i][j] > g[i][k] + g[k][j])
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g[i][j] = g[i][k] + g[k][j];
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if (g[i][i] < 0) return true; // 发现负圈
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}
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return false;
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}
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int main() {
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int T;
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cin >> T;
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while (T--) {
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cin >> n >> m >> w;
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memset(g, INF, sizeof g); // 初始化邻接矩阵
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// 双向正值边
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while (m--) {
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int a, b, c;
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cin >> a >> b >> c;
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// 注意坑：重边
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g[a][b] = g[b][a] = min(c, g[a][b]);
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}
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// 单向负值边
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while (w--) {
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int a, b, c;
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cin >> a >> b >> c;
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g[a][b] = -c; // 负值边
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}
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if (floyd())
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puts("YES");
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else
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puts("NO");
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}
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return 0;
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} |