B. Mike and Feet
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output
Mike is the president of country What-The-Fatherland. There are n bears living in this country besides Mike. All of them are standing in a line and they are numbered from 1 to n from left to right. i-th bear is exactly ai feet high.
A group of bears is a non-empty contiguous segment of the line. The size of a group is the number of bears in that group. The strengthof a group is the minimum height of the bear in that group.
Mike is a curious to know for each x such that 1 ≤ x ≤ n the maximum strength among all groups of size x.
Input
The first line of input contains integer n (1 ≤ n ≤ 2 × 105), the number of bears.
The second line contains n integers separated by space, a1, a2, ..., an (1 ≤ ai ≤ 109), heights of bears.
Output
Print n integers in one line. For each x from 1 to n, print the maximum strength among all groups of size x.
Example
10 1 2 3 4 5 4 3 2 1 6
Output
6 4 4 3 3 2 2 1 1 1Lets us understand few things(1) Lets consider that an element a[i] is smallest upto l on its left side and uptor on its right side In other words , a[l-1]>a[i] && a[r+1]>a[i]. Hence the element a[i] spans all the subsegments that starts from a[l] and covers atleast a[i] the element and and subsegment that covers a[i]th element and upto a[r].Lets call this as the spanof the subsegment. Let the length of span[a[i]]= r-l+1. Now lets this length be l. Hence this length is a canditate answer for any lenght t where t<=l .Now we simply calculate the maximum values of using the backward array and keeping in mind the fact that for any length l it can be a canditate answer for all length t such that1<=t<=l . Now how do we do this(1) o(n^2) logic :- for fixing the best answer for length l we take maximum values amongall the spans form length t where l<=t<=n. In other words ans[kth subsegment]=max(ans[k+1], ans[k+2],.....ans[n]); Doing this for all element will yield uso(n^2).(2) we reduce this to O(n) by setting the value from backward.***************************THE CODE FOLLOWS****************************#include<bits/stdc++.h> using namespace std; int a[200010]; int rt[200010]; int lt[200010]; int n; void calcspan() { stack<int> s; for(int i=1;i<=n;i++) { while(!s.empty() && a[s.top()]>a[i]) { rt[s.top()]=i-1; s.pop(); } s.push(i); } while(!s.empty()) { rt[s.top()]=n; s.pop(); } for(int i=n;i>=1;i--) { while(!s.empty() && a[s.top()]>a[i]) { lt[s.top()]=i+1; s.pop(); } s.push(i); } while(!s.empty()) { lt[s.top()]=1; s.pop(); } } int span[200010]; int maxi[200010]; int b[2000010]; int main() { //int n; cin>>n; for(int i=1;i<=n;i++) { cin>>a[i]; } calcspan(); for(int i=1;i<=n;i++) { span[i]=(rt[i]-lt[i]+1); } /* for(int i=1;i<=n;i++) { // cout<<span[i]<<" "; cout<<rt[i]<<" "; } cout<<endl; for(int i=1;i<=n;i++) { cout<<lt[i]<<" "; } cout<<endl; for(int i=1;i<=n;i++) cout<<span[i]<<" "; cout<<endl; cout<<endl;*/ for(int i=1;i<=n;i++) { maxi[span[i]]=max(maxi[span[i]],a[i]); } /* for(int i=1;i<=n;i++) cout<<maxi[i]<<" "; cout<<endl;*/ b[n+1]=0; for(int i=n;i>=1;i--) { b[i]=max(maxi[i],b[i+1]); } for(int i=1;i<=n;i++) cout<<b[i]<<" "; cout<<endl; }
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