Sliding Window
Time Limit: 12000MS | Memory Limit: 65536K | |
Total Submissions: 64320 | Accepted: 18327 | |
Case Time Limit: 5000MS |
Description
An array of size
n ≤ 10
6 is given to you. There is a sliding window of size
k which is moving from the very left of the array to the very right. You can only see the
k numbers in the window. Each time the sliding window moves rightwards by one position. Following is an example:
The array is [1 3 -1 -3 5 3 6 7], and k is 3.
The array is [1 3 -1 -3 5 3 6 7], and k is 3.
Window position | Minimum value | Maximum value |
---|---|---|
[1 3 -1] -3 5 3 6 7 | -1 | 3 |
1 [3 -1 -3] 5 3 6 7 | -3 | 3 |
1 3 [-1 -3 5] 3 6 7 | -3 | 5 |
1 3 -1 [-3 5 3] 6 7 | -3 | 5 |
1 3 -1 -3 [5 3 6] 7 | 3 | 6 |
1 3 -1 -3 5 [3 6 7] | 3 | 7 |
Your task is to determine the maximum and minimum values in the sliding window at each position.
Input
The input consists of two lines. The first line contains two integers
n and
k which are the lengths of the array and the sliding window. There are
n integers in the second line.
Output
There are two lines in the output. The first line gives the minimum values in the window at each position, from left to right, respectively. The second line gives the maximum values.
Sample Input
8 3 1 3 -1 -3 5 3 6 7
Sample Output
-1 -3 -3 -3 3 3 3 3 5 5 6 7
Source
POJ Monthly--2006.04.28, Ikki
题意:一个可移动的窗口长度为k,问在窗口从最左端移动到最右端每次移动时,最大值和最小值?
思路:单调队列。(学习了单调队列发现和单调栈思路挺像的,只不过每回取值都是取头所以只能用数组模拟)
这题用G++交会超时,改用C++交就可以A了。
#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
const int maxn=1e6+5;
int a[maxn];
int q1[maxn],q2[maxn];
int ans1[maxn],ans2[maxn];
int main()
{
int n,k;
while(~scanf("%d%d",&n,&k))
{
int head1=1,tail1=1,head2=1,tail2=1,j=1;
for(int i=1;i<=n;i++)
{
scanf("%d",&a[i]);
while(head1<tail1&&a[q1[tail1-1]]>a[i]) tail1--;
q1[tail1++]=i;
if(q1[head1]<i-k+1) head1++;
if(i>=k) ans1[j]=a[q1[head1]];
while(head2<tail2&&a[q2[tail2-1]]<a[i]) tail2--;
q2[tail2++]=i;
if(q2[head2]<i-k+1) head2++;
if(i>=k) ans2[j]=a[q2[head2]];
if(i>=k) j++;
}
for(int i=1;i<j;i++)
printf("%d ",ans1[i]);
printf("\n");
for(int i=1;i<j;i++)
printf("%d ",ans2[i]);
}
return 0;
}