最短路:Bellman-Ford
- 题目描述
- 参考代码
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;
}