bzoj4443 小凸玩矩阵

题目链接

二分+最大check

 #include<algorithm>
 #include<iostream>
 #include<cstdlib>
 #include<cstring>
 #include<cstdio>
 #include<string>
 #include<cmath>
 #include<ctime>
 #include<queue>
 #include<stack>
 #include<map>
 #include<set>
 #define rre(i,r,l) for(int i=(r);i>=(l);i--)
 #define re(i,l,r) for(int i=(l);i<=(r);i++)
 #define Clear(a,b) memset(a,b,sizeof(a))
 #define inout(x) printf("%d",(x))
 #define douin(x) scanf("%lf",&x)
 #define strin(x) scanf("%s",(x))
 #define LLin(x) scanf("%lld",&x)
 #define op operator
 #define CSC main
 typedef unsigned long long ULL;
 typedef const int cint;
 typedef long long LL;
 using namespace std;
 void inin(int &ret)
 {
     ret=;int f=;char ch=getchar();
     while(ch<''||ch>''){if(ch=='-')f=;ch=getchar();}
     while(ch>=''&&ch<='')ret*=,ret+=ch-'',ch=getchar();
     ret=f?-ret:ret;
 }
 int n,m,k,a[][],Max,s,t,ed;
 int head[],next[],zhi[],cap[];
 void add(int a,int b,int c)
 {
     next[++ed]=head[a],head[a]=ed,zhi[ed]=b,cap[ed]=c;
     next[++ed]=head[b],head[b]=ed,zhi[ed]=a,cap[ed]=;
 }
 queue<int>h;int dis[];
 bool bfs()
 {
     Clear(dis,);
     dis[s]=;h.push(s);
     while(!h.empty())
     {
         int x=h.front();h.pop();
         for(int i=head[x];i;i=next[i])if(cap[i]&&!dis[zhi[i]])
             dis[zhi[i]]=dis[x]+,h.push(zhi[i]);
     }
     return dis[t];
 }
 int dfs(int x,int Max)
 {
     if(!Max||x==t)return Max;
     int ret=,temp;
     for(int i=head[x];i;i=next[i])if(cap[i]&&dis[zhi[i]]==dis[x]+)
     {
         temp=dfs(zhi[i],min(Max,cap[i]));
         ret+=temp,Max-=temp;
         cap[i]-=temp,cap[i^]+=temp;
         if(!Max)return ret;
     }
     if(!ret)dis[x]=-;
     return ret;
 }
 int dinic()
 {
     int ret=;
     while(bfs())ret+=dfs(s,);
     return ret;
 }
 bool check(int x)
 {
     Clear(head,);ed=;
     re(i,,n)re(j,,m)
         if(a[i][j]<=x)add(i,j+n,);
     re(i,,n)add(s,i,);
     re(i,,m)add(i+n,t,);
     int ret=dinic();
     if(ret>=n-k+)return ;
     return ;
 }
 int main()
 {
     inin(n),inin(m),inin(k);s=n+m+,t=s+;
     re(i,,n)re(j,,m)inin(a[i][j]),Max=max(Max,a[i][j]);
     int l=,r=Max,mid,ans;
     while(l<=r)
     {
         mid=(l+r)>>;
         if(check(mid))ans=mid,r=mid-;
         else l=mid+;
     }
     printf("%d",ans);
     return ;
 }