luogu2569 [SCOI2010]股票交易

题解看这里

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;
int t, maxp, w, dp[2005][2005], qaq[2005], haq, taq, ap, bp, as, bs, ans;
int main(){
    cin>>t>>maxp>>w;
    memset(dp, 128, sizeof(dp));
    for(int i=1; i<=t; i++){
        scanf("%d %d %d %d", &ap, &bp, &as, &bs);
        for(int j=0; j<=as; j++)
            dp[i][j] = -1 * j * ap;
        for(int j=0; j<=maxp; j++)
            dp[i][j] = max(dp[i][j], dp[i-1][j]);
        if(i<=w)	continue;
        haq = 1; taq = 0;
        for(int j=0; j<=maxp; j++){
            while(haq<=taq && qaq[haq]<j-as)	haq++;
            while(haq<=taq && dp[i-w-1][qaq[taq]]+qaq[taq]*ap<=dp[i-w-1][j]+j*ap)	taq--;
            qaq[++taq] = j;
            if(haq<=taq)	dp[i][j] = max(dp[i][j], dp[i-w-1][qaq[haq]] + qaq[haq] * ap - j * ap);
        }
        haq = 1; taq = 0;
        for(int j=maxp; j>=0; j--){
            while(haq<=taq && qaq[haq]>j+bs)	haq++;
            while(haq<=taq && dp[i-w-1][qaq[taq]]+qaq[taq]*bp<=dp[i-w-1][j]+j*bp)	taq--;
            qaq[++taq] = j;
            if(haq<=taq)	dp[i][j] = max(dp[i][j], dp[i-w-1][qaq[haq]] + qaq[haq] * bp - j * bp);
        }
    }
    for(int i=0; i<=maxp; i++)
        ans = max(ans, dp[t][i]);
    cout<<ans<<endl;
    return 0;
}