bzoj1047 [HAOI2007]理想的正方形

题目：https://www.lydsy.com/JudgeOnline/problem.php?id=1047

不要想一个矩阵一个矩阵地弄。把行和列单独弄一下就行了。

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int N=1005;
int n,m,k,a[N][N],c1[N][N],c2[N][N],ans=0x7fffffff;
int q1[N],h1,t1,q2[N],h2,t2;
int main()
{
    scanf("%d%d%d",&n,&m,&k);
    for(int i=1;i<=n;i++)for(int j=1;j<=m;j++)scanf("%d",&a[i][j]);
    for(int i=1;i<=n;i++)
    {
        h1=1;t1=0;h2=1;t2=0;
        for(int j=1;j<=m;j++)
        {
            while(h1<=t1&&j-q1[h1]>=k)h1++;
            while(h2<=t2&&j-q2[h2]>=k)h2++;
            while(h1<=t1&&a[i][j]>=a[i][q1[t1]])t1--;q1[++t1]=j;
            while(h2<=t2&&a[i][j]<=a[i][q2[t2]])t2--;q2[++t2]=j;
            c1[i][j]=a[i][q1[h1]];c2[i][j]=a[i][q2[h2]];
        }
    }
    for(int j=1;j<=m;j++)
    {
        h1=1;t1=0;h2=1;t2=0;
        for(int i=1;i<=n;i++)
        {
            while(h1<=t1&&i-q1[h1]>=k)h1++;
            while(h2<=t2&&i-q2[h2]>=k)h2++;
            while(h1<=t1&&c1[i][j]>=c1[q1[t1]][j])t1--;q1[++t1]=i;
            while(h2<=t2&&c2[i][j]<=c2[q2[t2]][j])t2--;q2[++t2]=i;
            if(i>=k&&j>=k)ans=min(ans,c1[q1[h1]][j]-c2[q2[h2]][j]);
        }
    }
    printf("%d",ans);
    return 0;
}