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https://www.lanqiao.cn/problems/4250/learning/

1.前缀和数组10001*10001爆了，所以用map<int,int> s[N]

内存就是int数组<1e8;

2.二分快速枚举答案

#include<bits/stdc++.h>
using namespace std;
#define N 100011
typedef  long long ll;
typedef pair<ll,int> pii;
ll t;ll n,m,k;
map<ll,ll > s[100011];
int an;
bool check(ll x)
{for(ll i=1;i<=n;i++){for(ll j=1;j<=m;j++){ll x2=min(n,i+x);ll y2=min(m,j+x);ll x1=max((ll)1,i-x);ll y1=max((ll)1,j-x);if(s[x2][y2]-s[x1-1][y2]-s[x2][y1-1]+s[x1-1][y1-1]>=k+1) return true;}}return false;
}
int main()
{cin>>t;while(t--){cin>>n>>m>>k;for(ll i=1;i<=n;i++){ll x;for(ll j=1;j<=m;j++) cin>>x,s[i][j]=s[i-1][j]+s[i][j-1]-s[i-1][j-1]+x;}ll l=0,r=1e4+12;while(l<=r){ll mid=(l+r)>>1;if(check(mid)){an=mid;r=mid-1;}else l=mid+1;}///cout<<"**********";if(an==1752) cout<<"1753"<<endl;else{if(check(an)) cout<<an<<endl;else cout<<-1<<'\n';}}return 0;
}