Sliding Window
| Time Limit: 12000MS | Memory Limit: 65536K | |
| Total Submissions: 53037 | Accepted: 15207 | |
| Case Time Limit: 5000MS | ||
Description
An array of size n ≤ 106 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
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单调队列模板题。
维护两个单调队列，一个单调增，一个单调减。
1 #include<iostream> 2 #include<cstdio> 3 #include<cstring> 4 #include<cmath> 5 #include<algorithm> 6 #include<queue> 7 #include<cstdlib> 8 #include<iomanip> 9 #include<cassert> 10 #include<climits> 11 #define maxn 1000001 12 #define F(i,j,k) for(int i=j;i<=k;i++) 13 #define M(a,b) memset(a,b,sizeof(a)) 14 #define FF(i,j,k) for(int i=j;i>=k;i--) 15 #define inf 0x7fffffff 16 using namespace std; 17 int read(){ 18 int x=0,f=1;char ch=getchar(); 19 while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();} 20 while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();} 21 return x*f; 22 } 23 int a[maxn],q1[maxn],q2[maxn]; 24 int main() 25 { 26 std::ios::sync_with_stdio(false);//cout<<setiosflags(ios::fixed)<<setprecision(1)<<y; 27 #ifdef LOCAL 28 freopen("data.in","r",stdin); 29 freopen("data.out","w",stdout); 30 #endif 31 int n,m,k; 32 cin>>n>>k; 33 F(i,1,n) 34 { 35 cin>>a[i]; 36 } 37 int head=1,tail=0; 38 F(i,1,n) 39 { 40 while(head<=tail&&a[i]<=a[q1[tail]]) tail--; 41 q1[++tail]=i; 42 while(head<=tail&&q1[tail]-q1[head]>=k) head++; 43 if(i>=k) cout<<a[q1[head]]<<" "; 44 } 45 cout<<endl; 46 head=1,tail=0; 47 F(i,1,n) 48 { 49 while(head<=tail&&a[i]>=a[q2[tail]]) tail--; 50 q2[++tail]=i; 51 while(head<=tail&&q2[tail]-q2[head]>=k) head++; 52 if(i>=k) cout<<a[q2[head]]<<" "; 53 } 54 return 0; 55 }