萌新刚刚学C++，求调，马蜂良好

#include<bits/stdc++.h>
using namespace std;
int a,b,n,k,v[1005][1005],ans=INT_MAX;
int mav[1005][1005],miv[1005][1005];
#define c(x) 1<<x
int query(int x,int y){
    int mx=0,mi=0;
    mx=max({mav[x][y],mav[x+n-c(k)][y+n-c(k)],mav[x+n-c(k)][y],mav[x][y+n-c(k)]});
    mi=min({miv[x][y],miv[x+n-c(k)][y+n-c(k)],miv[x+n-c(k)][y],miv[x][y+n-c(k)]});
    return mx-mi;
}
int main(){
    cin>>a>>b>>n;
    for(int i=1;i<=a;i++){
    	for(int j=1;j<=b;j++){
            cin>>v[i][j];
            mav[i][j]=miv[i][j]=v[i][j];
        }
	}
    k=log2(n);
    for(int l=1;l<=k;l++){
    	for(int i=1;i+c(l)<=a;i++){
        	for(int j=1;j+c(l)<=b;j++){
                mav[i][j]=max(mav[i][j],max(mav[i+c(l)][j+c(l)],max(mav[i+c(l)][j],mav[i][j+c(l)])));
                miv[i][j]=min(miv[i][j],min(miv[i+c(l)][j+c(l)],min(miv[i+c(l)][j],miv[i][j+c(l)])));
            }
		}
	}
    for(int i=1;i<=a-n+1;i++){
    	for(int j=1;j<=b-n+1;j++){
        	ans=min(ans,query(i,j));
		}
	}
    cout<<ans;
    return 0;
}