单调队列

Posted 2021-02-17 universeplayer

luogu P1886 滑动窗口 https://www.luogu.org/problemnew/show/P1886

 1 // luogu-judger-enable-o2
 2 #include<bits/stdc++.h>
 3 using namespace std;
 4 #define il inline
 5 #define rg register
 6 typedef long long ll;
 7 #define max(a,b) (a)<(b)?(b):(a)
 8 #define gmax(a,b) a=max(a,b)
 9 #define min(a,b) (a)<(b)?(a):(b)
10 #define gmin(a,b) a=min(a,b)
11 #define FOR(i,a,b) for(rg int i=a;i<=b;++i)
12 #define For(i,a,b) for(rg int i=a;i>=b;--i)
13 #define gc pa==pb&&(pb=(pa=buf)+fread(buf,1,100000,stdin),pa==pb)?EOF:*pa++
14 static char buf[100000],*pa(buf),*pb(buf);
15 il int rd(){
16     rg int x(0),w(1);
17     rg char c(gc);
18     while(c<‘0‘||c>‘9‘)
19     {
20         if(c==‘-‘) w=-1;
21         c=gc;
22     }
23     while(c>=‘0‘&&c<=‘9‘) x=x*10+c-48,c=gc;
24     return x*w;}
25 const int N=1e6+5;
26 int q[N],hd,tl;
27 int n,k,a[N],ans;
28 
29 int main()
30 {
31     n=rd(),k=rd();
32     FOR(i,1,n) a[i]=rd();
33     hd=tl=1;ans=1e9;
34     FOR(i,1,k-1) 
35     {
36         while(hd<=tl && a[q[tl]]>=a[i]) --tl;
37         q[++tl]=i;
38     }
39     FOR(i,k,n)
40     {
41         while(hd<=tl && q[hd]<=i-k) ++hd;
42         while(hd<=tl && a[q[tl]]>=a[i]) --tl;
43         q[++tl]=i;
44         printf("%d ",a[q[hd]]);
45     }
46     printf("
");
47     hd=tl=1;ans=-(1e9);
48     FOR(i,1,k-1)
49     {
50         while(hd<=tl && a[q[tl]]<=a[i]) --tl;
51         q[++tl]=i;
52     }
53     FOR(i,k,n)
54     {
55         while(hd<=tl && q[hd]<=i-k) ++hd;
56         while(hd<=tl && a[q[tl]]<=a[i]) --tl;
57         q[++tl]=i;
58         printf("%d ",a[q[hd]]);
59     }
60     return 0;
61 }