直接倍增或者单调队列直接搞就好了吧。。。。没什么思维
虽然我就写了个滚动数组(数据太水了吧。。。。)
#include<bits/stdc++.h>
#define MAXN 1000
using namespace std;
int a,b,n;
long long f[MAXN+5][MAXN+5][3],g[MAXN+5][MAXN+5][3],ans=999999999;//最大以及最小值
void init(){
memset(f,0,sizeof(f));
memset(g,0x7f,sizeof(f));
cin>>a>>b>>n;
for(int i=1;i<=a;i++)for(int j=1;j<=b;j++)scanf("%lld",&f[i][j][1]),g[i][j][1]=f[i][j][1];
}
void solve(){
for(int k=2;k<=n;k++){
for(int i=1;i<=a;i++){
if(i-k+1<1)continue;
for(int j=1;j<=b;j++){
if(j-k+1<1)continue;
f[i][j][k%2] = max(f[i][j][k%2],f[i][j][(k+1)%2]);
f[i][j][k%2] = max(f[i][j][k%2],f[i-1][j][(k+1)%2]);
f[i][j][k%2] = max(f[i][j][k%2],f[i][j-1][(k+1)%2]);
f[i][j][k%2] = max(f[i][j][k%2],f[i-1][j-1][(k+1)%2]);
g[i][j][k%2] = min(g[i][j][k%2],g[i][j][(k+1)%2]);
g[i][j][k%2] = min(g[i][j][k%2],g[i-1][j][(k+1)%2]);
g[i][j][k%2] = min(g[i][j][k%2],g[i][j-1][(k+1)%2]);
g[i][j][k%2] = min(g[i][j][k%2],g[i-1][j-1][(k+1)%2]);
}
}
}
for(int i=1;i<=a;i++){if(i-n+1<1)continue;
for(int j=1;j<=b;j++){if(j-n+1<1)continue;
ans = min(ans,f[i][j][n%2]-g[i][j][n%2]);
}
}
cout<<ans<<endl;
}
int main(){
init();
solve();
}