acm竞赛的常用模板,非常的全面,对算法的各个方面都有涉及,阅读以后能极大的提高自己的算法能力

				//求上下界网络最大流,邻接表形式
				//返回最大流量,-1表示无可行流,flow返回每条边的流量
				//传入网络节点数n,容量mat,流量下界bf,源点source,汇点sink
				//MAXN应比最大结点数多2,无可行流返回-1时mat未复原!
				
				#define MAXN 100
				#define inf 1000000000
				
				int _max_flow(int n,int mat[][MAXN],int source,int sink,int flow[][MAXN]){
					int pre[MAXN],que[MAXN],d[MAXN],p,q,t,i,j,r;
					vector e[MAXN];	
					for (i=0;i						for (e[i].clear(),j=0;j							if (mat[i][j]) e[i].push_back(j),e[j].push_back(i);
					for (;;){
						for (i=0;i						pre[t=source]=source+1,d[t]=inf;
						for (p=q=0;p							for (r=0;r								i=e[t][r];			
								if (!pre[i]&&(j=mat[t][i]-flow[t][i]))
									pre[que[q++]=i]=t+1,d[i]=d[t]								else if (!pre[i]&&(j=flow[i][t]))
									pre[que[q++]=i]=-t-1,d[i]=d[t]							}
						if (!pre[sink]) break;
						for (i=sink;i!=source;)
							if (pre[i]>0)
								flow[pre[i]-1][i]+=d[sink],i=pre[i]-1;
							else
								flow[i][-pre[i]-1]-=d[sink],i=-pre[i]-1;
					}
					for (j=i=0;i					return j;
				}
				int limit_max_flow(int n,int mat[][MAXN],int bf[][MAXN],int source,int sink,int flow[][MAXN]){
					int i,j,sk,ks;
					if (source==sink) return inf;
					for (mat[n][n+1]=mat[n+1][n]=mat[n][n]=mat[n+1][n+1]=i=0;i						for (mat[n][i]=mat[i][n]=mat[n+1][i]=mat[i][n+1]=j=0;j							mat[i][j]-=bf[i][j],mat[n][i]+=bf[j][i],mat[i][n+1]+=bf[i][j];
					sk=mat[source][sink],ks=mat[sink][source],mat[source][sink]=mat[sink][source]=inf;
					for (i=0;i						for (j=0;j					_max_flow(n+2,mat,n,n+1,flow);
					for (i=0;i						if (flow[n][i]					flow[source][sink]=flow[sink][source]=0,mat[source][sink]=sk,mat[sink][source]=ks;
					_max_flow(n,mat,source,sink,flow);
					for (i=0;i						for (j=0;j							mat[i][j]+=bf[i][j],flow[i][j]+=bf[i][j];
					for (j=i=0;i					return j;
				}