Internship

  1 #include<iostream>
  2 #include<cstring>
  3 #include<algorithm>
  4 #include<cstdio>
  5 #include<queue>
  6 #define INF 100000000
  7 using namespace std;
  8 const int N=1305;
  9 const int M=40000;
 10 struct Node{
 11    int v;
 12    int f;
 13    int next;
 14 }edge[M];
 15 int n,m,u,v,l,w,cnt,sx,ex;
 16 int head[N],pre[N];
 17 int ans[N],top;
 18 int from[N],to[N];
 19 bool vis1[N],vis2[N];
 20 void init(){
 21     cnt=0;
 22     memset(head,-1,sizeof(head));
 23     memset(vis1,0,sizeof(vis1));
 24     memset(vis2,0,sizeof(vis2));
 25 }
 26 void add(int u,int v,int w,int id){
 27     edge[cnt].v=v;
 28     edge[cnt].f=w;
 29     edge[cnt].next=head[u];
 30     head[u]=cnt++;
 31     edge[cnt].f=0;
 32     edge[cnt].v=u;
 33     edge[cnt].next=head[v];
 34     head[v]=cnt++;
 35 }
 36 bool BFS(){
 37   memset(pre,0,sizeof(pre));
 38   pre[sx]=1;
 39   queue<int>Q;
 40   Q.push(sx);
 41  while(!Q.empty()){
 42      int d=Q.front();
 43      Q.pop();
 44      for(int i=head[d];i!=-1;i=edge[i].next    ){
 45         if(edge[i].f&&!pre[edge[i].v]){
 46             pre[edge[i].v]=pre[d]+1;
 47             Q.push(edge[i].v);
 48         }
 49      }
 50   }
 51  return pre[ex]>0;
 52 }
 53 int dinic(int flow,int ps){
 54     int f=flow;
 55      if(ps==ex)return f;
 56      for(int i=head[ps];i!=-1;i=edge[i].next){
 57         if(edge[i].f&&pre[edge[i].v]==pre[ps]+1){
 58             int a=edge[i].f;
 59             int t=dinic(min(a,flow),edge[i].v);
 60               edge[i].f-=t;
 61               edge[i^1].f+=t;
 62             flow-=t;
 63             if(flow<=0)break;
 64         }
 65 
 66      }
 67      if(f-flow<=0)pre[ps]=-1;
 68       return f-flow;
 69 }
 70 void solve(){
 71     int sum=0;
 72     while(BFS())
 73         sum+=dinic(INF,sx);
 74 }
 75 void DFS1(int u,int fa){
 76    if(vis1[u])return;
 77     vis1[u]=1;
 78    for(int i=head[u];i!=-1;i=edge[i].next){
 79       if(edge[i].f>0){
 80          DFS1(edge[i].v,u);
 81       }
 82    }
 83 }
 84 void DFS2(int u,int fa){
 85    if(vis2[u])return;
 86     vis2[u]=1;
 87    for(int i=head[u];i!=-1;i=edge[i].next){
 88       if(edge[i^1].f>0){
 89          DFS2(edge[i].v,u);
 90       }
 91    }
 92 }
 93 int main() {
 94     while(~scanf("%d%d%d",&n,&m,&l)&&n) {
 95          init();
 96        for(int i=1;i<=l;i++){
 97         scanf("%d%d%d",&from[i],&to[i],&w);
 98           add(from[i],to[i],w,i);
 99        }
100        for(int i=1;i<=n;i++){
101          add(m+n+1,i,INF,0);
102        }
103        sx=n+m+1,ex=0;
104        solve();
105        DFS1(sx,sx);
106        DFS2(ex,ex);
107        top=0;
108        for(int i=1;i<=l;i++){
109            int u=from[i],v=to[i];
110          if(vis1[u]&&vis2[v])
111             ans[++top]=i;
112        }
113        if(top==0)puts("");
114        else{
115           sort(ans+1,ans+top+1);
116           for(int i=1;i<top;i++)
117             printf("%d ",ans[i]);
118            printf("%d\n",ans[top]);
119        }
120     }
121     return 0;
122 }