2012 icpc 长春赛区的最大流模板题, 模板的高效性很重要
#include <cstdio>#include <cstring>#include <queue>#include <algorithm>#define MAXVERTEX100001#define MAXARC 400010#define INF0x7fffffff#pragma comment(linker, "/STACK:1024000000,1024000000")using namespace std; struct Edge{int v, val, next;}edge[MAXARC];int vertex, e_gap, head[MAXVERTEX];int pre[MAXVERTEX], cur[MAXVERTEX], dis[MAXVERTEX], gap[MAXVERTEX];void insert_arc(int u, int v, int w){edge[e_gap].v = v;edge[e_gap].val = w;edge[e_gap].next = head[u];head[u] = e_gap ++;swap(u, v);edge[e_gap].v = v;edge[e_gap].val = 0;edge[e_gap].next = head[u];head[u] = e_gap ++;}void bfs(int source, int sink){int u, v;queue<int> q;memset(dis, -1, sizeof(dis));memset(gap, 0, sizeof(gap));dis[sink] = 0;gap[0] = 1;q.push(sink);while( !q.empty() ) {u = q.front(); q.pop();for(int i = head[u]; -1 != i; i = edge[i].next) {v = edge[i].v;if( edge[i].val || -1 != dis[v] )continue;dis[v] = dis[u]+1;gap[ dis[v] ] ++;q.push(v);}}}int i_sap(int source, int sink){int u(source), v, min_dis, max_flow(0), path_flow(INF);bfs(source, sink);for(int i = 0; i <= vertex; i ++)cur[i] = head[i];gap[0] = vertex; pre[u] = u;while( dis[source] < vertex ) {loop:for(int &i = cur[u]; -1 != i; i = edge[i].next) {v = edge[i].v;if( !edge[i].val || (dis[u] != dis[v]+1) )continue;pre[v] = u;path_flow = min(path_flow, edge[i].val);u = v;if( v == sink ) {for(u = pre[u]; v != source; v = u, u = pre[u]) {edge[cur[u]].val -= path_flow;edge[cur[u]^1].val += path_flow;}max_flow += path_flow; path_flow = INF;}goto loop;}min_dis = vertex;for(int i = head[u]; -1 != i; i = edge[i].next) {v = edge[i].v;if( edge[i].val && min_dis > dis[v] ) {cur[u] = i; min_dis = dis[v];}}gap[ dis[u] ] --;if( !gap[ dis[u] ] )break;dis[u] = min_dis+1;gap[ dis[u] ] ++;u = pre[u];}return max_flow;}int main(int argc, char const *argv[]){//freopen("test.in", "r", stdin);int cas, arc, source, sink, x, y, v, max_x, min_x;scanf("%d", &cas);while( cas-- ) {scanf("%d %d", &vertex, &arc);max_x = -INF; min_x = INF;for(int i = 1; i <= vertex; i ++) {scanf("%d %d", &x, &y);if( min_x > x ) {min_x = x;source = i;}if( max_x < x ) {max_x = x; sink = i;}}e_gap = 0;memset(head, -1, sizeof(head));for(int i = 0; i < arc; i ++) {scanf("%d %d %d", &x, &y, &v);insert_arc(x, y, v);insert_arc(y, x, v);}printf("%d\n", i_sap(source, sink));}return 0;}
