poj 2823 Sliding Window

http://poj.org/problem?id=2823

　　入门级的单调队列，不过我的代码要用cout加上poj的g++才能3500ms左右通过，不然就会超时了！

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <iostream>

using namespace std;

const int maxn = 1000001;

void scan(int &n){
    char ch;

    while ((ch = getchar()) != '-' && ('0' > ch || ch > '9'));
    if (ch != '-'){
        n = ch - '0';
        while ((ch = getchar()) >= '0' && ch <= '9')
            n = n * 10 + ch - '0';
    }
    else{
        n = 0;
        while ((ch = getchar()) >= '0' && ch <= '9')
            n = n * 10 + '0' - ch;
    }
}

int qmx[maxn], imx[maxn], qmxh, qmxt;
int qmn[maxn], imn[maxn], qmnh, qmnt;
int rec[maxn];

int main(){
    int n, k, a;

    scan(n);
    scan(k);
    qmxh = qmxt = qmnh = qmnt = 0;

    for (int i = 0; i < n; i++){
        scan(a);
        while (qmxh < qmxt && qmx[qmxt - 1] <= a) qmxt--;
        qmx[qmxt] = a;
        imx[qmxt++] = i;
        while (qmnh < qmnt && qmn[qmnt - 1] >= a) qmnt--;
        qmn[qmnt] = a;
        imn[qmnt++] = i;

        if (i < k - 1) continue;
        if (i - imx[qmxh] >= k) qmxh++;
        if (i - imn[qmnh] >= k) qmnh++;
        cout << qmn[qmnh] << ' ';
        //printf("%d ", qmn[qmnh]);
        rec[i] = qmx[qmxh];
    }
    puts("");
    for (int i = k - 1; i < n; i++)
        cout << rec[i] << ' ';
        //printf("%d ", rec[i]);
    puts("");

    return 0;
}

——written by Lyon