hdu1845 Jimmy’s Assignment (最大匹配Hopcroft-Karp算法)

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题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1845

#include <cstdio>  #include <queue>  #include <vector>  #include <cstring>  #include <cmath>  #define MAXN 5001 using namespace std;   int nx,ny,distx[MAXN],disty[MAXN];  int visited[MAXN],mx[MAXN],my[MAXN];  vector<int> graphics[MAXN];  queue<int> Q;   int Scan(){char ch;int ret=0;while((ch=getchar())<'0'||ch>'9');while(ch>='0'&&ch<='9'){ret=ret*10+(ch-'0');ch=getchar();}return ret;}int find(int u)  {//寻找增广路  int i,temp;  for(i=0;i<graphics[u].size();++i) {  temp=graphics[u][i];  if(!visited[temp]&&(disty[temp]==distx[u]+1))  {  visited[temp]=1;  if(!my[temp]||find(my[temp]))  {  mx[u]=temp;  my[temp]=u;  return 1;  }  }  }  return 0;  }  int search()  {  int temp,u,flag=0;  memset(distx,0,sizeof(distx));  memset(disty,0,sizeof(disty));  while(!Q.empty())  Q.pop();  for(int i=1;i<=nx;++i)  {  if(!mx[i])  Q.push(i);  }  while(!Q.empty())  {  u=Q.front();  Q.pop();  for(int i=0;i<graphics[u].size();++i)  {  temp=graphics[u][i];  if(!disty[temp])  {  disty[temp]=distx[u]+1;  if(my[temp])  {  distx[my[temp]]=disty[temp]+1;  Q.push(my[temp]);  }  else  flag=1;  }  }  }  return flag;  }  int matching()  {  int ans=0;  memset(mx,0,sizeof(mx));  memset(my,0,sizeof(my));  while(search())  {  memset(visited,0,sizeof(visited));  for(int i=1;i<=nx;++i)  if(!mx[i]&&find(i))  ans++;  }  return ans;  }  int main()  {  int n,u,v,sum,test,N;scanf("%d",&test);while(test--){scanf("%d",&n);N=(n>>1)*3;for(int i=0;i<=n;++i)  graphics[i].clear(); while(N--)  {  //scanf("%d %d",&u,&v); u=Scan();v=Scan();graphics[u].push_back(v); //用邻接表  graphics[v].push_back(u); //建双向图    }     nx=ny=n;sum=matching();printf("%d\n",sum/2);  }return 0;  }

#include<stdio.h>    int main()  {      int t,n,i,x,y;      scanf("%d",&t);      while(t--)      {          scanf("%d",&n);          for(i=0;i<n*3/2;i++)          scanf("%d%d",&x,&y);          printf("%d\n",n/2);      }      return 0;  }