最短路：Bellman-Ford

题目描述

输入样例

3 3 1
1 2 1
2 3 1
1 3 3

输出样例

3

参考代码

#include <iostream>
#include <cstring>
#include <algorithm>using namespace std;const int N = 510, M = 10010;int n, m, k;
int dist[N], backup[N];     // 需要备份struct
{int a, b, w;
} edges[M];int bellman_ford()
{memset(dist, 0x3f, sizeof dist);dist[1] = 0;for (int i = 0; i < k; i++){memcpy(backup, dist, sizeof dist);for (int j = 0; j < m; j++){int a = edges[j].a, b = edges[j].b, w = edges[j].w;dist[b] = min(dist[b], backup[a] + w);}}if (dist[n] > 0x3f3f3f3f / 2) return -1;return dist[n];
}int main()
{scanf("%d%d%d", &n, &m, &k);for (int i = 0; i < m; i++){int a, b, w;scanf("%d%d%d", &a, &b, &w);edges[i] = {a, b, w};}int ans = bellman_ford();printf("%d\n", ans);return 0;
}