LeetCode in Kotlin

1261. Find Elements in a Contaminated Binary Tree

Medium

Given a binary tree with the following rules:

1. root.val == 0
2. If treeNode.val == x and treeNode.left != null, then treeNode.left.val == 2 * x + 1
3. If treeNode.val == x and treeNode.right != null, then treeNode.right.val == 2 * x + 2

Now the binary tree is contaminated, which means all treeNode.val have been changed to -1.

Implement the FindElements class:

• FindElements(TreeNode* root) Initializes the object with a contaminated binary tree and recovers it.
• bool find(int target) Returns true if the target value exists in the recovered binary tree.

Example 1:

Input [“FindElements”,”find”,”find”] [[[-1,null,-1]],[1],[2]]

Output: [null,false,true]

Explanation:

FindElements findElements = new FindElements([-1,null,-1]); 
findElements.find(1); // return False 
findElements.find(2); // return True

Example 2:

Input [“FindElements”,”find”,”find”,”find”] [[[-1,-1,-1,-1,-1]],[1],[3],[5]]

Output: [null,true,true,false]

Explanation:

FindElements findElements = new FindElements([-1,-1,-1,-1,-1]); 
findElements.find(1); // return True 
findElements.find(3); // return True 
findElements.find(5); // return False

Example 3:

Input [“FindElements”,”find”,”find”,”find”,”find”] [[[-1,null,-1,-1,null,-1]],[2],[3],[4],[5]]

Output: [null,true,false,false,true]

Explanation:

FindElements findElements = new FindElements([-1,null,-1,-1,null,-1]); 
findElements.find(2); // return True 
findElements.find(3); // return False 
findElements.find(4); // return False 
findElements.find(5); // return True

Constraints:

• TreeNode.val == -1
• The height of the binary tree is less than or equal to 20
• The total number of nodes is between [1, 104]
• Total calls of find() is between [1, 104]
• 0 <= target <= 106

Solution

import com_github_leetcode.TreeNode

/*
 * Example:
 * var ti = TreeNode(5)
 * var v = ti.`val`
 * Definition for a binary tree node.
 * class TreeNode(var `val`: Int) {
 *     var left: TreeNode? = null
 *     var right: TreeNode? = null
 * }
 */
class FindElements(root: TreeNode?) {
    private val map = HashMap<Int, Int>()

    init {
        helper(root, 0)
    }

    private fun helper(root: TreeNode?, x: Int) {
        if (root == null) {
            return
        }
        root.`val` = x
        map[x] = 0
        helper(root.left, 2 * x + 1)
        helper(root.right, 2 * x + 2)
    }

    fun find(target: Int): Boolean {
        return map.containsKey(target)
    }
}
/*
 * Your FindElements object will be instantiated and called as such:
 * var obj = FindElements(root)
 * var param_1 = obj.find(target)
 */

This site is open source. Improve this page.