cf round # 618 E monotonous stack

Meaning of the questions:

An array of n give you, you can many times, so that the selection interval values ​​within the range are added, and then all of the average value interval becomes.

Making the final array lexicographically smallest

Ideas:

The final array must be monotonically increasing, as long as it is larger than the average of the previous number, it will not operate if younger than him, it is necessary to operate in line with its scope

Operate with monotonically decreasing Stack

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 #define ll long long
 4 #define il inline
 5 #define it register int
 6 #define inf 0x3f3f3f3f
 7 #define lowbit(x) (x)&(-x)
 8 #define mem(a,b) memset(a,b,sizeof(a))
 9 #define mod 1000000007
10 const int maxn=1e6+10;
11 int n,m,t;
12 double a[maxn],ans[maxn];
13 int l[maxn],len[maxn];
14 int main(){
15     scanf("%d",&n);
16     for(it i=1;i<=n;i++){
17         scanf("%lf",&a[i]);len[i]=1;
18     }
19     it top=1;l[1]=1;
20     for(it i=2;i<=n;i++){
21         double now=a[i],sum=a[i];
22         while(top>=1 && a[l[top]]>now){
23             len[i]+=len[l[top]];
24             sum+=a[l[top]]*len[l[top]];
25             now=sum/len[i];
26             top--;
27         }
28         a[i]=sum/len[i];
29         l[++top]=i;
30     }
31     it l1=0;
32     while(top>=1){
33         for(it i=1;i<=len[l[top]];i++){
34             ans[++l1]=a[l[top]];
35         }top--;
36     }
37     for(it i=l1;i;i--){
38         printf("%.10lf\n",ans[i]);
39     }
40     return 0;
41 }

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