1 /* 2 唐代杜荀鹤 3 《小松》 4 自小刺头深草里，而今渐觉出蓬蒿。 5 时人不识凌云木，直待凌云始道高。 6 */ 7 #include <iostream> 8 #include <cstdio> 9 #include <algorithm> 10 #include <cstring> 11 #include <vector> 12 #include <utility> 13 #include <iomanip> 14 #include <string> 15 #include <cmath> 16 #include <queue> 17 #include <assert.h> 18 #include <map> 19 #include <ctime> 20 #include <cstdlib> 21 #include <stack> 22 #include <set> 23 #define LOCAL 24 const int INF = 0x7fffffff; 25 const int MAXN = 100000 + 10; 26 const int maxnode = 20000 * 2 + 200000 * 20; 27 const int MAXM = 50000 + 10; 28 const int MAX = 100; 29 using namespace std; 30 struct Edge{ 31 int u, v, c, f; 32 void init(int a, int b, int d, int e){ 33 u = a;v = b; 34 c = d;f = e; 35 } 36 }edges[MAXM]; 37 int next[MAXN], M, cur[MAXN], vis[MAXN]; 38 int dist[MAXN], head[MAXN], n, m, sta, end; 39 40 void addEdge(int u, int v, int c){ 41 edges[M].init(u, v, c, 0);M++; 42 edges[M].init(v, u, 0, 0);//反向边 43 next[M - 1] = head[u]; 44 head[u] = M - 1; 45 next[M] = head[v]; 46 head[v] = M++; 47 return; 48 } 49 void init(){ 50 M = 0;//总边数 51 memset(head, -1, sizeof(head)); 52 scanf("%d%d", &n, &m); 53 for (int i = 1; i <= m; i++){ 54 int u, v, c; 55 scanf("%d%d%d", &u, &v, &c); 56 addEdge(u, v, c); 57 } 58 sta = 1; 59 end = n; 60 } 61 bool bfs(){ 62 memset(vis, 0, sizeof(vis)); 63 queue<int>Q; 64 dist[sta] = 0; 65 vis[sta] = 1; 66 Q.push(sta); 67 while (!Q.empty()){ 68 int u = Q.front(); 69 Q.pop(); 70 for (int i = head[u]; i != -1; i = next[i]){ 71 int e = i, v = edges[e].v; 72 if (vis[v]) continue; 73 if (edges[e].c > edges[e].f){ 74 vis[v] = 1; 75 dist[v] = dist[u] + 1; 76 Q.push(v); 77 } 78 } 79 } 80 return vis[end]; 81 } 82 int dfs(int x, int a){ 83 if (x == end || a == 0) return a; 84 int flow = 0, f; 85 if (cur[x] == -1) cur[x] = head[x]; 86 for (int &i = cur[x]; i != -1; i = next[i]){ 87 int e = i, v = edges[i].v; 88 if (dist[v] == dist[x] + 1 && (f = dfs(v, min(edges[e].c - edges[e].f, a))) > 0){ 89 flow += f; 90 a -= f; 91 edges[e].f += f; 92 edges[e ^ 1].f -= f; 93 if (a == 0) break; 94 } 95 } 96 return flow; 97 } 98 int Dinic(){ 99 int flow = 0; 100 while (bfs()){ 101 memset(cur, -1, sizeof(cur)); 102 flow += dfs(sta, INF); 103 } 104 return flow; 105 } 106 107 int main(){ 108 #ifdef LOCAL 109 freopen("data.txt", "r", stdin); 110 freopen("out.txt", "w", stdout); 111 #endif 112 init(); 113 printf("%d", Dinic()); 114 //printf("%d", (a == c)); 115 return 0; 116 }