hdu_3549

最大流

#include <stdio.h>#include <string.h>#include <algorithm>#define MAXVERTEX 20#define MAXARC 2001#define INF0x7fffffffusing namespace std;struct Edge {int v, w, next;}edge[MAXARC];int vertex, arc, cnt_edge, head[MAXVERTEX];int pre[MAXVERTEX], dis[MAXVERTEX], cur[MAXVERTEX], gap[MAXVERTEX];void Insert_Edge( int u , int v , int w ) {edge[cnt_edge].v = v;edge[cnt_edge].w = w;edge[cnt_edge].next = head[u];head[u] = cnt_edge ++;}int i_sap(int source, int sink){int u(source), v, min_dis, max_flow(0), path_flow(INF);memset(gap, 0, sizeof(gap));memset(dis, 0, sizeof(dis));for(int i = 0; i <= sink; i ++)cur[i] = head[i];gap[0] = sink;pre[source] = source;while( dis[source] < sink ) {loop:for( int &i = cur[u]; -1 != i; i = edge[i].next ) {v = edge[i].v;if( !edge[i].w || (dis[u] != dis[v]+1) ) continue;pre[v] = u; path_flow = min(path_flow, edge[i].w); u = v;if( v == sink ) {for(u = pre[u]; v != source; v = u, u = pre[u]) {edge[cur[u]].w -= path_flow; edge[cur[u]^1].w += path_flow;}max_flow += path_flow; path_flow = INF;}goto loop;}min_dis = sink;for(int i = head[u]; -1 != i; i = edge[i].next) {v = edge[i].v;if( edge[i].w && (min_dis > dis[v]) ) {cur[u] = i; min_dis = dis[v];}}if( --gap[dis[u]] == 0 ) break;gap[ dis[u] = min_dis+1 ]++;u = pre[u];}return max_flow;}int main(int argc, char const *argv[]){//freopen("test.in", "r", stdin);int cnt(1), cas, s, f, v;scanf("%d", &cas);while( cas-- ) {cnt_edge = 0;scanf("%d %d", &vertex, &arc);memset(head, -1, sizeof(int)*vertex);for(int i = 0; i < arc; i ++) {scanf("%d %d %d", &s, &f, &v);Insert_Edge(s, f, v);Insert_Edge(f, s, 0);}printf("Case %d: %d\n", cnt ++, i_sap(1, vertex));}return 0;}