[poj2823]Sliding Window（单调队列）
题意：给定一个序列，求所有滑动窗口内的最值。
解题关键：单调队列裸题，单调递增队列选取最小值，单调递减队列选取最大值。
注意用c++提交，否则会超时。
1 #include<cstdio> 2 #include<cstring> 3 #include<algorithm> 4 #include<cstdlib> 5 #include<iostream> 6 #include<cmath> 7 #define maxn 1000005 8 using namespace std; 9 typedef long long ll; 10 int n,k; 11 int min1[maxn],max1[maxn],pos1[maxn],que1[maxn],a[maxn]; 12 inline int read(){ 13 char k=0;char ls;ls=getchar();for(;ls<'0'||ls>'9';k=ls,ls=getchar()); 14 int x=0;for(;ls>='0'&&ls<='9';ls=getchar())x=(x<<3)+(x<<1)+ls-'0'; 15 if(k=='-')x=0-x;return x; 16 } 17 inline void get_min(int n,int k){ 18 int head=0,rear=0; 19 for(int i=1;i<k;i++){ 20 while(rear>head&&que1[rear-1]>a[i]) rear--; 21 que1[rear]=a[i]; 22 pos1[rear]=i; 23 rear++; 24 } 25 for(int i=k;i<=n;i++){ 26 while(rear>head&&que1[rear-1]>a[i]) rear--; 27 que1[rear]=a[i]; 28 pos1[rear]=i; 29 rear++; 30 while(pos1[head]<i-k+1) head++; 31 min1[i]=que1[head]; 32 } 33 } 34 inline void get_max(int n,int k){ 35 int head=0,rear=0; 36 for(int i=1;i<k;i++){ 37 while(rear>head&&que1[rear-1]<a[i]) rear--; 38 que1[rear]=a[i]; 39 pos1[rear]=i; 40 rear++; 41 } 42 for(int i=k;i<=n;i++){ 43 while(rear>head&&que1[rear-1]<a[i]) rear--; 44 que1[rear]=a[i]; 45 pos1[rear]=i; 46 rear++; 47 while(pos1[head]<i-k+1) head++; 48 max1[i]=que1[head]; 49 } 50 } 51 int main(){ 52 while(scanf("%d%d",&n,&k)!=EOF){ 53 for(int i=1;i<=n;i++) a[i]=read(); 54 get_min(n,k); 55 get_max(n,k); 56 for(int i=k;i<=n;i++){ 57 printf("%d%c",min1[i],i==n?'\n':' '); 58 } 59 for(int i=k;i<=n;i++){ 60 printf("%d%c",max1[i],i==n?'\n':' '); 61 } 62 } 63 }
