传送门

程序：

#include <bits/stdc++.h>
using namespace std;

const int N=3e2;

int a,b,k;

int _a[N][N],number[N][N],_b[N][N];

int get(int pos1X,int pos1Y)
{
	int x=pos1X-k,y=pos1Y-k;
	swap(x,pos1X);
	swap(y,pos1Y);
	int answer=number[x][y]-number[pos1X][y]-number[x][pos1Y]+number[pos1X][pos1Y];
	return answer;
}

int main()
{
	int answer=0,x,y;
	cin>>a>>b>>k;
	k--;k--;
	for (int i=1;i<=a;i++)
	{
		string temp="";
		cin>>temp;
		for (int j=0;j<b;j++)
		{
			if (temp[j]=='*') _a[i][j+1]=1;
		}
	}
	for (int i=1;i<=a;i++)
	{
		for (int j=1;j<=b;j++)
		{
			number[i][j]=number[i-1][j]+number[i][j-1]-number[i-1][j-1]+_a[i][j];
		}
	}
	for (int i=2;i<=a-1;i++)
	{
		for (int j=2;j<=b-1;j++)
		{
			if (answer!=max(answer,get(i,j)))
			{
				answer=max(answer,get(i,j));x=i;y=j;
			}
		}
	}cout<<answer<<endl;
	for (int i=1;i<=a;i++)
	{
		for (int j=1;j<=b;j++)
		{
			if (i==x+1 && j==y+1 || i==x-k && j==y-k || i==x+1 && j==y-k || i==x-k && j==y+1){cout<<"+";continue;}
			if (j<=y && j>=y-k+1 && i==x-k || i==x+1 && j<=y && j>=y-k+1){cout<<"-";continue;}
			if (i<=x && i>=x-k+1 && j==y-k || j==y+1 && i<=x && i>=x-k+1){cout<<"|";continue;}
			if (_a[i][j]==0) cout<<".";
			if (_a[i][j]==1) cout<<"*";
		}
		cout<<endl;
	}
	
	return 0;
}

不知道哪里出了问题 dalao速助 orz