bzoj4443:[Scoi2015]小凸玩矩阵

传送门

二分答案是显然的啊，然后对于比二分出的值大的直接跑最大匹配，然后判定就好了
代码：

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<vector>
#include<cstring>
using namespace std;
void read(int &x) {char ch; bool ok;for(ok=0,ch=getchar(); !isdigit(ch); ch=getchar()) if(ch=='-') ok=1;for(x=0; isdigit(ch); x=x*10+ch-'0',ch=getchar()); if(ok) x=-x;
}
#define rg register
const int maxn=260;
int n,m,k,f[maxn],ans,a[maxn][maxn];bool vis[maxn],used[maxn][maxn];
bool dfs(int x)
{for(rg int i=1;i<=m;i++)if(!used[x][i]&&!vis[i]){vis[i]=1;if(!f[i]||dfs(f[i])){f[i]=x;return 1;}}return 0;
}
bool check(int v)
{memset(f,0,sizeof f),memset(used,0,sizeof used),ans=0;for(rg int i=1;i<=n;i++)for(rg int j=1;j<=m;j++)if(a[i][j]>=v)used[i][j]=1;for(rg int i=1;i<=n;i++){memset(vis,0,sizeof vis);if(dfs(i))ans++;}return ans>=n-k+1;
}
int main()
{read(n),read(m),read(k);for(rg int i=1;i<=n;i++)for(rg int j=1;j<=m;j++)read(a[i][j]);int l=0,r=1e9;while(l<=r){int mid=(l+r)>>1;if(check(mid))r=mid-1;else l=mid+1;}printf("%d\n",r);
}