단조로운 대기열 최적화 dp

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define INF 0x7fffffff
using namespace std;
int n,m,x,t;
int sum[105][10005];
void input()
{
    int x;
    for(int i=1; i<=n; i++)
    {
        sum[i][0]=0;
        for(int j=1; j<=m; j++)
        {
            scanf("%d",&x);
            sum[i][j]=sum[i][j-1]+x;
        }
    }
}
struct node
{
    int m,pos;
};
node q[10005];
int dp[105][10005];
int solve()
{
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=m;j++)
        dp[i][j]=-500000005;
    }
    for(int i=1;i<=m;i++)
    dp[0][i]=-500000005;
    dp[0][x]=0;
    for(int i=1;i<=n;i++)
    {
        //dp[i-1][k1]-sum[i][k1-1]
        int head=1,tail=0;
        for(int j=1;j<=m;j++)
        {
            int tmp=dp[i-1][j]-sum[i][j-1];
            while(head<=tail&&q[tail].m<=tmp) tail--;
            q[++tail].m=tmp;
            q[tail].pos=j;
            while(head<=tail&&q[head].pos<j-t) head++;
            dp[i][j]=max(dp[i][j],q[head].m+sum[i][j]);
        }
        head=1,tail=0;
        for(int j=m;j>=1;j--)
        {
            int tmp=dp[i-1][j]+sum[i][j];
            while(head<=tail&&q[tail].m<=tmp) tail--;
            q[++tail].m=tmp;
            q[tail].pos=j;
            while(head<=tail&&q[head].pos>j+t) head++;
            dp[i][j]=max(dp[i][j],q[head].m-sum[i][j-1]);
        }
    }
    int ans=-500000005;
    for(int i=1;i<=m;i++) ans=max(ans,dp[n][i]);
    return ans;
}
int main()
{
    while(scanf("%d%d%d%d",&n,&m,&x,&t)!=EOF)
    {
        input();
        printf("%d
",solve());
    }
    return 0;
}