Last Updated: 12 May, 2022

Locked Binary Tree

Easy
Asked in company
Walmart

Problem statement

Given array ‘PAR’ of size ‘N’, representing a binary tree, where ‘PAR[i]’ denotes the parent of node ‘i’. And a binary array ‘LOCK’ of ‘N’ integers, ‘LOCK[i] = 1’ means the ‘ith’ node is locked. Find out whether a target node ‘K’ can be locked or not.

A node will be locked only when some or all of the ancestors or the node itself is locked.

EXAMPLE:
Input: 
'N' = 5, ‘K’ = 3
‘ARR’ = [-1, 0, 0, 1, 2]
‘LOCK’ = [0, 0, 1, 0, 0]

Output: ‘1’

In the above tree in the simple path from node ‘4’ to root ‘1,’ the nodes encountered are [0, 1, 3], and no node from the set is locked. Hence node ‘3’ can be locked.
Input Format :
The first line will contain the integer 'T', the number of test cases. For each test case

The first line of each test case contains two integers ‘N’, and ‘K’.
The second line of each test case contains ‘N’ integers denoting the parent of node ‘i’.
The third line of each test case contains ‘N’ integers denoting elements of array ‘LOCK’.
Output format :
For each test case, print ‘1’ or ’0’, denoting whether the node can be locked.
Note :
You don't need to print anything. It has already been taken care of. Just implement the given function.
Constraints :
1 <= 'T' <= 10
1 <= 'N' <= 10^5
0 <= ‘K’ <= ‘N-1’
0 <= ‘PAR[i]’ <= ‘N-1’
0 <= ‘LOCK[i]’ <= 1    

Time Limit: 1 sec

Approaches

01 Approach

Approach: 
 

  1. Travel from the target node to the root and see if any node in between is locked or not.
     

Algorithm :  
 

  • Create and initialize a boolean variable ‘RES’ as ‘true’.
  • Do a while loop from our target node ‘K’ to ‘ROOT’
    • If any encountered node is locked, set ‘RES’ to false.
  • Return ‘RES’.