1 //SPFA，邻接表存储，参数分别是：边数组，索引数组，源点，保存结果数组，总节点数
2 //返回true表示找到最短路，false表示有负环
3 void addedge(EDGE *edge,int* idx,int a,int b,int d,int totedge)
4 {
5 edge[totedge].to = b; edge[totedge].dis = d; edge[totedge].next= idx[a]; idx[a] = totedge;
6 }
7 struct EDGE
8 {
9 int to,dis,next;
10 }edge1[MAXN*MAXN],edge2[MAXN*MAXN];
11 bool spfa(EDGE *edge,int *idx,int start,int *dis,int n)
12 {
13 int i,a,b,cnt[MAXN];
14 bool inque[MAXN];
15 queue<int> que;
16 memset(cnt,0,sizeof(cnt));
17 memset(inque,false,sizeof(inque));
18 memset(dis,0x3f,sizeof(int)*MAXN);
19 dis[start] = 0; inque[start] = true; cnt[start] = 1;
20 while(!que.empty()) que.pop();
21 que.push(start);
22 while(!que.empty())
23 {
24 a = que.front(); que.pop(); inque[a] = false;
25 for(i=idx[a]; i!= -1; i = edge[i].next)
26 {
27 b = edge[i].to;
28 if(dis[b] - edge[i].dis > dis[a])
29 {
30 dis[b] = dis[a] + edge[i].dis;
31 if(! inque[b])
32 {
33 inque[b] = true; que.push(b);
34 if(++cnt[b] > n)
35 {
36 return false;
37 }
38 }
39 }
40 }
41 }
42 return true;
43 }
