poj2823_单调队列简单入门

题目链接：http://poj.org/problem?id=2823

#include<iostream>
#include<cstdio>
#define M 1000001
using namespace std;

int n,k;
int a[M];
int q[M];
int p[M];

void get_min()
{
    int head=;
    int tail=;
    for(int i=;i<k-;i++)
    {
        while(head<=tail&&a[i]<=q[tail])
            --tail;
        q[++tail]=a[i];
        p[tail]=i;
    }
    for(int i=k-;i<n;i++)
    {
        while(head<=tail&&a[i]<=q[tail])
            --tail;
        q[++tail]=a[i];
        p[tail]=i;
        while(p[head]<i-k+)
        {
            ++head;
        }
        cout<<q[head]<<" ";
    }
    cout<<endl;
}

void get_max()
{
    int head=;
    int tail=;
    for(int i=;i<k-;i++)
    {
        while(head<=tail&&a[i]>=q[tail])
            --tail;
        q[++tail]=a[i];
        p[tail]=i;
    }
    for(int i=k-;i<n;i++)
    {
        while(head<=tail&&a[i]>=q[tail])
            --tail;
        q[++tail]=a[i];
        p[tail]=i;
        while(p[head]<i-k+)
        {
            ++head;
        }
        cout<<q[head]<<" ";
    }
    cout<<endl;
}

int main()
{
    //freopen("d:\\test.txt","r",stdin);
    scanf("%d%d",&n,&k);
    for(int i=;i<n;i++)
    {
        scanf("%d",&a[i]);
    }
    get_min();
    get_max();
    return ;
}