参考模板：

#include<bits/stdc++.h>
using namespace std;
#define INF 0x3f3f3f3f
typedef long long ll;struct node {int v, dis;node(int v, int dis) {this->v = v, this->dis = dis;}
};
vector<node> adj[1005];
int n, d[1005], num[1005];
bool inq[1005];bool SPFA(int s)
{fill(d, d + 1005, INF);priority_queue<int> q;  //priority_queue只能用top取元素，因为其实质是个堆q.push(s);inq[s] = true;num[s]++;d[s] = 0;while (!q.empty()){int u = q.top();q.pop();inq[u] = false;for (int i = 0; i < adj[u].size();i++){int v = adj[u][i].v;int dis = adj[u][i].dis;if (d[u] + dis < d[v]){d[v] = d[u] + dis;if (!inq[v]){q.push(v);inq[v] = true;num[v]++;if (num[v] >= n) return false;  //若有负权环，入队次数一定超过n}}}}return true;
}bool bellman(int s)
{fill(d, d + 1005, INF);for (int i = 0; i < n - 1; i++){for (int j = 0; j < n; j++){for (int k = 0; k < adj[j].size(); j++){int v = adj[j][k].v;int dis = adj[j][k].dis;if (d[j] + dis < d[v]){d[v] = d[j] + dis;}}}}for (int j = 0; j < n; j++){for (int k = 0; k < adj[j].size(); j++){int v = adj[j][k].v;int dis = adj[j][k].dis;if (d[j] + dis < d[v]) return false;}}return true;
}int main()
{//主函数按需补充return 0;
}