HDU 3251 Being a Hero 最小割

  1 #include <iostream>
  2 #include <string.h>
  3 #include <stdio.h>
  4 #include <vector>
  5 #include <queue>
  6 #define INF 0x3f3f3f3f
  7 using namespace std;
  8 const int M = 210010;
  9 struct Nod {
 10     int to, cap, next, index;
 11 }edge[M];
 12 int T, n, m, f, s, t;
 13 int head[M], level[M], vis[M], iter[M], sum, num;
 14 void init() {
 15     memset(head, -1, sizeof(head));
 16     memset(vis, 0, sizeof(vis));
 17     num = 0;
 18     sum = 0;
 19 }
 20 void add_edge(int u, int v, int cap, int index) {
 21     edge[num].to = v; edge[num].cap = cap; edge[num].next = head[u]; edge[num].index = index; head[u] = num++;
 22     edge[num].to = u; edge[num].cap = 0; edge[num].next = head[v]; edge[num].index = -1; head[v] = num++;
 23 }
 24 bool bfs(int s, int t) {
 25     memset(level, -1, sizeof(level));
 26     level[s] = 0;
 27     queue<int> que;
 28     que.push(s);
 29     while(!que.empty()) {
 30         int v = que.front();
 31         que.pop();
 32         for(int i = head[v]; i != -1; i = edge[i].next) {
 33             int u = edge[i].to;
 34             if(level[u] < 0 && edge[i].cap) {
 35                 level[u] = level[v] + 1;
 36                 que.push(u);
 37             }
 38         }
 39     }
 40     return level[t] != -1;
 41 }
 42 int dfs(int v, int t, int f) {
 43     if(v == t) return f;
 44     for(int &i = iter[v]; i != -1; i = edge[i].next) {
 45         int u = edge[i].to;
 46         if(level[u] > level[v] && edge[i].cap > 0) {
 47             int d = dfs(u, t, min(f, edge[i].cap));
 48             if(d > 0) {
 49                 edge[i].cap -= d;
 50                 edge[i^1].cap += d;
 51                 return d;
 52             }
 53         }
 54     }
 55     level[v] = -1;
 56     return 0;
 57 }
 58 int max_flow(int s, int t) {
 59     int flow = 0;
 60     while(bfs(s, t)) {
 61         for(int i = 0; i <= t + 10; i ++) iter[i] = head[i];
 62         int f = 0;
 63         while((f = dfs(s, t, INF)) > 0) flow += f;
 64     }
 65     return flow;
 66 }
 67 void dfs(int u, int fa) {
 68     for(int i = head[u]; i != -1; i = edge[i].next) {
 69         int v = edge[i].to;
 70         if(!vis[v] && edge[i].cap) {
 71             vis[v] = true;
 72             dfs(v, u);
 73         }
 74     }
 75 }
 76 int main() {
 77     ios::sync_with_stdio(false);
 78     // cin >> T;
 79     scanf("%d", &T);
 80     int cas = 1;
 81     while(T--) {
 82         // cin >> n >> m >> f;
 83         scanf("%d %d %d", &n, &m, &f);
 84         init();
 85         add_edge(s, 1, INF, -1);
 86         s = 0, t = n + 1;
 87         for(int i = 1; i <= m; i ++) {
 88             int u, v, w;
 89             scanf("%d %d %d", &u, &v, &w);
 90             add_edge(u, v, w, i);
 91         }
 92         for(int i = 1; i <= f; i ++) {
 93             int u, w;
 94             scanf("%d %d", &u, &w);
 95             add_edge(u, t, w, -1);
 96             sum += w;
 97         }
 98         int ans = max_flow(s, t);
 99         ans = sum - ans;
100         printf("Case %d: %d\n",cas++, ans);
101         vis[1] = true;
102         dfs(1, -1);
103         queue<int> que;
104         for(int i = 0; i < num; i += 2) {//0正1负
105             if(vis[edge[i^1].to] && !vis[edge[i].to] && edge[i].index != -1) que.push(edge[i].index);
106         }
107         printf("%d",(int)que.size());
108         while(!que.empty()) {
109             printf(" %d",que.front());
110             que.pop();
111         }
112         printf("\n");
113     }
114     return 0;
115 }