hdu 4374 单调队列优化dp

#include<iostream>#include<cstdio>#include<cstring>#include<algorithm>#define INF 0x7fffffffusing 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\n",solve());    }    return 0;}