L2-035 sequence traversal of complete binary tree (25 points)

​​​​​​ Topic details - L2-035 Sequence traversal of complete binary tree (25 branch ) (pintia.cn)

Ideas ： Perfect binary tree （ If the root node is i, Left son for i*2, The right son is i*2+1）, Its sequence traversal is ：1,2,3,……,n. With this conclusion, we can directly simulate the input of post order traversal , Then output the array in sequence .

#include<iostream>
using namespace std;
const int N = 40;
int a[N];
int n; 
void dfs(int u){
    int l = u*2, r= u*2+1;
    if(l <= n) dfs(l);
    if(r <= n) dfs(r);
    cin>>a[u];
}
int main(){
    cin>>n;
    dfs(1);
    for(int i = 1; i <= n; i++){
    	if(i != 1) cout<<' ';
        cout<<a[i];
    }
    return 0;
}