HDU 3530 Subsequence (dp+单调队列)

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <queue>
using namespace std;

const int maxn = 100010;

int a[maxn];

int main()
{
    int n,m,k;
    while(~scanf("%d%d%d",&n,&m,&k)){
        for(int i=1;i<=n;i++)
            scanf("%d",&a[i]);
        deque<int > mmax;
        deque<int > mmin;
        int ans = 0;
        int st = 0;
        for(int i=1;i<=n;i++){
            while(!mmax.empty()&&a[i]>a[mmax.back()]) mmax.pop_back();//维护单调性
            while(!mmin.empty()&&a[i]<a[mmin.back()]) mmin.pop_back();//维护单调性
            mmax.push_back(i);
            mmin.push_back(i);
            while(!mmax.empty()&&!mmin.empty()&&a[mmax.front()]-a[mmin.front()]>k){
                if(mmax.front()<mmin.front()){
                    st = mmax.front();
                    mmax.pop_front();
                }
                else {
                    st=mmin.front();
                    mmin.pop_front();
                }
            }
            if(!mmax.empty()&&!mmin.empty()&&a[mmax.front()]-a[mmin.front()]>=m)
                ans = max(ans,i-st);
        }
        cout<<ans<<endl;
    }
    return 0;
}