poj 3259 Wormholes ： spfa 双端队列优化 判负环 O(k*E)

 /**
 problem: http://poj.org/problem?id=3259
 spfa判负环：
 当有个点被松弛了n次，则这个点必定为负环中的一个点（n为点的个数）
 spfa双端队列优化：
 维护队列使其dist小的点优先处理
 **/
 #include<stdio.h>
 #include<deque>
 #include<algorithm>
 using namespace std;

 class Graphics{
 const static int MAXN = ;
 const static int MAXM =  *  + ;
 const static int INF = 0x7fffffff;
 private:
     struct Edge{
         int to, dist, next;
     }edge[MAXM];
     int first[MAXN], sign, sumOfPoint;
 public:
     void init(int n){
         sumOfPoint = n;
         for(int i = ; i <= n; i ++){
             first[i] = -;
         }
         sign = ;
     }
     void addEdgeOneWay(int u, int v, int w){
         edge[sign].dist = w;
         edge[sign].to = v;
         edge[sign].next = first[u];
         first[u] = sign ++;
     }
     void addEdgeTwoWay(int u, int v, int w){
         addEdgeOneWay(u, v, w);
         addEdgeOneWay(v, u, w);
     }
     bool spfaNegRing(int start){
         bool *vis = new bool[sumOfPoint+];
         int *dist = new int[sumOfPoint+];
         int *cnt = new int[sumOfPoint+];
         for(int i = ; i <= sumOfPoint; i ++){
             vis[i] = ;
             cnt[i] = ;
             dist[i] = INF;
         }
         deque<int> que;
         que.push_front(start);
         dist[start] = ;
         vis[start] = ;
         while(!que.empty()){
             int now = que.front();
             que.pop_front();
             vis[now] = ;
             for(int i = first[now]; i != -; i = edge[i].next){
                 int to = edge[i].to, eDist = edge[i].dist;
                 if(dist[now] + eDist < dist[to]){
                     dist[to] = dist[now] + eDist;
                     cnt[to] ++;
                     if(cnt[to] >= sumOfPoint) { /// 如果这个点已经松弛n次则它必定是负环中的一个点
                         delete []vis; delete []dist; return true;
                     }
                     if(!vis[to]){
                         vis[to] = ;
                         if(que.empty() || dist[to] <= dist[que.front()])
                             que.push_front(to);
                         else
                             que.push_back(to);
                     }
                 }
             }
         }
         delete []vis; delete []dist; return false;
     }
 }graph;

 int main(){
     int f;
     scanf("%d", &f);
     while(f --){
         int n, m, w;
         scanf("%d%d%d", &n, &m, &w);
         graph.init(n);
         while(m --){
             int s, e, t;
             scanf("%d%d%d", &s, &e, &t);
             graph.addEdgeTwoWay(s, e, t);
         }
         while(w --){
             int s, e, t;
             scanf("%d%d%d", &s, &e, &t);
             graph.addEdgeOneWay(s, e, -t);
         }
         printf("%s\n", graph.spfaNegRing() ? "YES" : "NO");
     }
     return ;
 }