题目链接:http://poj.org/problem?id=3281
看了kuangbin大佬的思路,还用着kuangbin板子orz http://www.cnblogs.com/kuangbin/archive/2012/08/21/2649850.html
#include<cstdio> #include<cstring> using namespace std; const int MAXN = 10010; const int MAXM = 40010; const int INF = 0x3f3f3f3f; struct Edge { int to,next,cap,flow; } edge[MAXM]; int tol; int head[MAXN]; int gap[MAXN],dep[MAXN],pre[MAXN],cur[MAXN]; void init() { tol = 0; memset(head,-1,sizeof(head)); } void addedge(int u,int v,int w,int rw=0) { edge[tol].to = v; edge[tol].cap = w; edge[tol].next = head[u]; edge[tol].flow = 0; head[u] = tol++; edge[tol].to = u; edge[tol].cap = rw; edge[tol].next = head[v]; edge[tol].flow = 0; head[v]=tol++; } int sap(int start,int end,int N) { memset(gap,0,sizeof(gap)); memset(dep,0,sizeof(dep)); memcpy(cur,head,sizeof(head)); int u = start; pre[u] = -1; gap[0] = N; int ans = 0; while(dep[start] < N) { if(u == end) { int Min = INF; for(int i = pre[u]; i != -1; i = pre[edge[i^1].to]) if(Min > edge[i].cap - edge[i].flow) Min = edge[i].cap - edge[i].flow; for(int i = pre[u]; i != -1; i = pre[edge[i^1].to]) { edge[i].flow += Min; edge[i^1].flow -= Min; } u = start; ans += Min; continue; } bool flag = false; int v; for(int i = cur[u]; i != -1; i = edge[i].next) { v = edge[i].to; if(edge[i].cap - edge[i].flow && dep[v]+1 == dep[u]) { flag = true; cur[u] = pre[v] = i; break; } } if(flag) { u = v; continue; } int Min = N; for(int i = head[u]; i != -1; i = edge[i].next) if(edge[i].cap - edge[i].flow && dep[edge[i].to] < Min) { Min = dep[edge[i].to]; cur[u] = i; } gap[dep[u]]--; if(!gap[dep[u]])return ans; dep[u] = Min+1; gap[dep[u]]++; if(u != start) u = edge[pre[u]^1].to; } return ans; } int main() { int n,F,D; scanf("%d%d%d",&n,&F,&D); init(); for (int i=0;i<n;i++) addedge(i,i+n,1); for (int i=0;i<n;i++) { int f,d; scanf("%d%d",&f,&d); for (int j=0;j<f;j++) { int x; scanf("%d",&x); x--; addedge(n+n+x,i,1); } for (int j=0;j<d;j++) { int x; scanf("%d",&x); x--; addedge(n+i,n+n+F+x,1); } } for (int i=0;i<F;i++) addedge(n+n+F+D,n+n+i,1); for (int i=0;i<D;i++) addedge(n+n+F+i,n+n+F+D+1,1); printf("%d",sap(n+n+F+D,n+n+F+D+1,n+n+F+D+2)); return 0; }