POJ 2823 Sliding Window

梦里梦外; 2022-07-08 14:28 128阅读 0赞

Sliding Window

<table> 
 <tbody> 
 <tr> 
 <td>Time Limit:&nbsp;12000MS</td> 
 <td>&nbsp;</td> 
 <td>Memory Limit:&nbsp;65536K</td> 
 </tr> 
 <tr> 
 <td>Total Submissions:&nbsp;58579</td> 
 <td>&nbsp;</td> 
 <td>Accepted:&nbsp;16778</td> 
 </tr> 
 <tr> 
 <td colspan="3" align="center" style="color:rgb(14,173,0)">Case Time Limit:&nbsp;5000MS</td> 
 </tr> 
 </tbody> 
</table>

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.

<table> 
 <tbody> 
 <tr> 
 <th>Window position</th> 
 <th>Minimum value</th> 
 <th>Maximum value</th> 
 </tr> 
 <tr> 
 <td>[1&nbsp;&nbsp;3&nbsp;&nbsp;-1]&nbsp;-3&nbsp;&nbsp;5&nbsp;&nbsp;3&nbsp;&nbsp;6&nbsp;&nbsp;7&nbsp;</td> 
 <td align="RIGHT">-1</td> 
 <td align="RIGHT">3</td> 
 </tr> 
 <tr> 
 <td>&nbsp;1&nbsp;[3&nbsp;&nbsp;-1&nbsp;&nbsp;-3]&nbsp;5&nbsp;&nbsp;3&nbsp;&nbsp;6&nbsp;&nbsp;7&nbsp;</td> 
 <td align="RIGHT">-3</td> 
 <td align="RIGHT">3</td> 
 </tr> 
 <tr> 
 <td>&nbsp;1&nbsp;&nbsp;3&nbsp;[-1&nbsp;&nbsp;-3&nbsp;&nbsp;5]&nbsp;3&nbsp;&nbsp;6&nbsp;&nbsp;7&nbsp;</td> 
 <td align="RIGHT">-3</td> 
 <td align="RIGHT">5</td> 
 </tr> 
 <tr> 
 <td>&nbsp;1&nbsp;&nbsp;3&nbsp;&nbsp;-1&nbsp;[-3&nbsp;&nbsp;5&nbsp;&nbsp;3]&nbsp;6&nbsp;&nbsp;7&nbsp;</td> 
 <td align="RIGHT">-3</td> 
 <td align="RIGHT">5</td> 
 </tr> 
 <tr> 
 <td>&nbsp;1&nbsp;&nbsp;3&nbsp;&nbsp;-1&nbsp;&nbsp;-3&nbsp;[5&nbsp;&nbsp;3&nbsp;&nbsp;6]&nbsp;7&nbsp;</td> 
 <td align="RIGHT">3</td> 
 <td align="RIGHT">6</td> 
 </tr> 
 <tr> 
 <td>&nbsp;1&nbsp;&nbsp;3&nbsp;&nbsp;-1&nbsp;&nbsp;-3&nbsp;&nbsp;5&nbsp;[3&nbsp;&nbsp;6&nbsp;&nbsp;7]</td> 
 <td align="RIGHT">3</td> 
 <td align="RIGHT">7</td> 
 </tr> 
 </tbody> 
</table>

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

#include <iostream>
 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 #include <deque>
 #include <vector>
 using namespace std;
 const int maxn = 1000000 + 5;
 int mmax[maxn];
 int mmin[maxn];
 int a[maxn];
 int n,k;
 struct node
 {
 int key;
 int value;
 }vis[maxn];
 int MAX[maxn],MIN[maxn];
 int n,k;
 deque<node> q1,q2;
 
 void _min()
 {
 for(int i=1;i<=n;++i)
 {
 while(!q1.empty())
 {
 if(q1.back().value > vis[i].value) q1.pop_back();
 else break;
 }
 q1.push_back(vis[i]);
 while(!q1.empty())
 {
 if(q1.front().key<i-k+1) q1.pop_front();
 else break;
 }
 MIN[i]=q1.front().value;
 }
 }
 void _max()
 {
 for(int i=1;i<=n;++i)
 {
 while(!q2.empty())
 {
 if(q2.back().value < vis[i].value) q2.pop_back();
 else break;
 }
 q2.push_back(vis[i]);
 while(!q2.empty())
 {
 if(q2.front().key<i-k+1) q2.pop_front();
 else break;
 }
 MAX[i]=q2.front().value;
 }
 }
 
 int main()
 {
 cin>>n>>k;
 for(int i=1;i<=n;++i)
 {
 cin>>vis[i].value;
 vis[i].key=i;
 }
 _min();
 _max();
 for(int i=k;i<n;++i)
 {
 cout<<MIN[i]<<" ";
 }
 cout<<MIN[n]<<endl;
 for(int i=k;i<n;++i)
 {
 cout<<MAX[i]<<" ";
 }
 cout<<MAX[n]<<endl;
 return 0;
 }

[POJ Monthly--2006.04.28]: http://poj.org/searchproblem?field=source&key=POJ+Monthly--2006.04.28