# Bellman-Ford（贝尔曼，福特）算法——解决负权边

## Dijkstra算法不能解决带有负权边的图（边的权值为负数）。而Bellman-Ford算法可以解决这个问题

``````#include<iostream>
using namespace std;
int main() {
int dis[10], bak[10];//bac用来备份dis
int n, m, u[10], v[10], w[10], check, flag;
int inf = 99999999;//无穷大
cout << " 输入顶点个数和边的条数" << endl;
cin >> n >> m;
for (int i = 1; i <= m; i++)//读入边
cin >> u[i] >> v[i] >> w[i];//从u到v的边权是w
for (int i = 1; i <= n; i++)
dis[i] = inf;//初始化数组
dis[1] = 0;
for (int k = 1; k <= n - 1; k++) {//bellman算法
for (int i = 1; i <= n; i++)
bak[i] = dis[i];//备份数组
for (int i = 1; i <= m; i++) {//进行一轮松弛
if (dis[v[i]] > dis[u[i]] + w[i])
dis[v[i]] = dis[u[i]] + w[i];
check = 0;//检测dis是否需要更新
}
for (int i = 1; i <= n; i++) {
if (bak[i] != dis[i]) {
check = 1;
break;
}
}
if (check == 0)//如果没有更新提前结束算法
break;
}
//检测负权回路
flag = 0;
for (int i = 1; i <= n; i++)
if (dis[v[i]] > dis[u[i]] + w[i])
flag = 1;
if (flag == 1)
cout << "含有负权回路" << endl;
else{
for (int i = 1; i <= n; i++)
cout << dis[i] << " ";
}
return 0;
}``````

原文作者：Bellman - ford算法
原文地址: https://blog.csdn.net/Icarus_/article/details/50808512
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