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预处理出二维前缀和

预处理出每个以(i,j)为右下角的A*B矩阵的和

预处理出每个以(i,j)为右下角的C*D矩阵的和

先用单调队列出列的C*D的最小值

再用另一个单调队列处理出行的

然后枚举比较即可

照着代码意会

#include<bits/stdc++.h>
namespace ZDY{
    #pragma GCC optimize(3)
    #define il __inline__ __attribute__ ((always_inline))
    #define rg register
    #define ll long long
    #define ull unsigned long long
    #define db double
    #define sht short
    #define MB template <class T>il
    #define Fur(i,x,y) for(int i=x;i<=y;i++)
    #define Fdr(i,x,y) for(int i=x;i>=y;i--)
    #define fl(i,x) for(int i=head[x],to;to=e[i].to,i;i=e[i].nxt)
    #define clr(x,y) memset(x,y,sizeof(x))
    #define cpy(x,y) memcpy(x,y,sizeof(x))
    #define fin(s) freopen(s".in","r",stdin)
    #define fout(s) freopen(s".out","w",stdout)
    #define fcin ios::sync_with_stdio(false)
    #define l2(n) (int(log2(n)))
    #define inf 0x3f3f3f3f
    MB T ABS(T x){return x>0?x:-x;}
    MB T MAX(T x,T y){return x>y?x:y;}
    MB T MIN(T x,T y){return x<y?x:y;}
    MB T GCD(T x,T y){return y?GCD(y,x%y):x;}
    MB void SWAP(T &x,T &y){T t=x;x=y;y=t;}
}using namespace ZDY;using namespace std;
namespace IO{const char* ln="\n";const int str=1<<20;struct IN{char buf[str],*s,*t;bool _;IN():s(buf),t(buf),_(0){}il char gc(){return s==t&&((t=(s=buf)+fread(buf,1,str,stdin))==s)?EOF:(*s++);}IN&operator>>(char&ch){if(_)return *this;char c;while((c=gc())!=EOF&&isspace(c));if(c==EOF)_=1;else ch=c;return *this;}IN& operator>>(char* ch){if(_)return *this;char c;while((c=gc())!=EOF&&isspace(c));if(c==EOF)return _=1,*this;*ch=c;ch++;while((c=gc())!=EOF&&!isspace(c))*ch=c,ch++;if(c==EOF)_=1;return *this;}IN& operator>>(string& ch){if(_)return *this;char c;while((c=gc())!=EOF&&isspace(c));if(c==EOF)return _=1,*this;ch+=c;while((c=gc())!=EOF&&!isspace(c))ch+=c;if(c==EOF)_=1;return *this;}template<typename T>IN&operator>>(T&x){if(_)return *this;char c=gc();bool ff=0;while(c!=EOF&&(c<'0'||c>'9'))ff^=(c=='-'),c=gc();if(c==EOF){_=1;return *this;}x=0;while(c!=EOF&&'0'<=c&&c<='9')x=(x<<3)+(x<<1)+c-48,c=gc();if(c==EOF)_=1;if(ff)x=-x;return *this;}}in;struct OUT{char buf[str],*s,*t;OUT():s(buf),t(buf+str){}~OUT(){fwrite(buf,1,s-buf,stdout);}void pt(char c){(s==t)?(fwrite(s=buf,1,str,stdout),*s++=c):(*s++=c);}OUT&operator<<(const char*s){while(*s)pt(*s++);return *this;}OUT&operator<<(char*s){while(*s)pt(*s++);return *this;}OUT&operator<<(string s){for(int i=0;s[i];i++)pt(s[i]);return *this;}template<typename T>OUT&operator<<(T x){if(!x)return pt('0'),*this;if(x<0)pt('-'),x=-x;char a[30],t=0;while(x)a[t++]=x%10,x/=10;while(t--)pt(a[t]+'0');return *this;}}out;}using namespace IO;
#define N 1011
int n,m,A,B,C,D,Q[N];
int s[N][N],a[N][N],b[N][N],p[N][N],q[N][N];
int main(){
    in>>n>>m>>A>>B>>C>>D;
    Fur(i,1,n)
        Fur(j,1,m)
        in>>s[i][j],s[i][j]+=s[i-1][j]+s[i][j-1]-s[i-1][j-1];

    Fur(i,C+1,n-1)
        Fur(j,D+1,m-1)
        a[i][j]=s[i][j]-s[i][j-D]-s[i-C][j]+s[i-C][j-D];

    Fur(i,A,n)
        Fur(j,B,m)
        b[i][j]=s[i][j]-s[i][j-B]-s[i-A][j]+s[i-A][j-B];

    Fur(i,C+1,n-1){
        int h=1,t=0;
        Fur(j,D+1,m-1){
            while(h<=t&&Q[h]<j-B+D+2)h++;
            while(h<=t&&a[i][Q[t]]>=a[i][j])t--;
            Q[++t]=j;
            if(j>=B-1)p[i][j+1]=a[i][Q[h]];
        }
    }

    Fur(j,B,m){
        int h=1,t=0;
        Fur(i,C+1,n-1){
            while(h<=t&&Q[h]<i-A+2+C)h++;
            while(h<=t&&p[Q[t]][j]>=p[i][j])t--;
            Q[++t]=i;
            if(i>=A-1)q[i+1][j]=p[Q[h]][j];
        }
    }
    int ans=0;
    Fur(i,A,n)
        Fur(j,B,m)
        ans=MAX(ans,b[i][j]-q[i][j]);

    out<<ans<<ln;
}
LG 2219 [HAOI2007]修筑绿化带
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