51nod 1437 迈克步（单调栈）

 1 #include<iostream>
 2 #include<algorithm>
 3 #include<cstring>
 4 #include<cstdio>
 5 #include<vector>
 6 #include<stack>
 7 #include<queue>
 8 #include<cmath>
 9 #include<map>
10 #include<set>
11 using namespace std;
12 typedef long long ll;
13 typedef pair<int,int> pll;
14 const int INF = 0x3f3f3f3f;
15 const int maxn = 2*1e5+5;
16 
17 int n;
18 int a[maxn];
19 int sta[maxn];
20 int l[maxn], r[maxn];
21 int ans[maxn];
22 
23 int main()
24 {
25     //freopen("in.txt","r",stdin);
26     while(~scanf("%d",&n))
27     {
28         memset(ans,0,sizeof(ans));
29         for(int i=1;i<=n;i++)  scanf("%d",&a[i]);
30         int top = 0;
31         for(int i=1;i<=n;i++)
32         {
33             while(top && a[sta[top]]>=a[i])  top--;
34             if(top==0)   l[i]=1;
35             else l[i]=sta[top]+1;
36             sta[++top]=i;
37         }
38         top = 0;
39         for(int i=n;i>=1;i--)
40         {
41             while(top && a[sta[top]]>a[i])  top--;
42             if(top==0)   r[i]=n;
43             else r[i]=sta[top]-1;
44             sta[++top]=i;
45         }
46         for(int i=1;i<=n;i++)
47             ans[r[i]-l[i]+1]=max(ans[r[i]-l[i]+1],a[i]);
48         for(int i=n-1;i>=1;i--)
49             ans[i]=max(ans[i],ans[i+1]);
50         for(int i=1;i<=n;i++)
51             printf("%d%c",ans[i],i==n?‘\n‘:‘ ‘);
52     }
53     return 0;
54 }