Day 86 of 100 Days LeetCode Challenge

LeetCode Challenge #112. Path Sum

Given the root of a binary tree and an integer targetSum, return true if the tree has a root-to-leaf path such that adding up all the values along the path equals targetSum.

leaf is a node with no children.

 

Example 1:

pathsum1

Input: root = [5,4,8,11,null,13,4,7,2,null,null,null,1], targetSum = 22
Output: true
Explanation: The root-to-leaf path with the target sum is shown.

Example 2:

pathsum2

Input: root = [1,2,3], targetSum = 5
Output: false
Explanation: There two root-to-leaf paths in the tree:
(1 --> 2): The sum is 3.
(1 --> 3): The sum is 4.
There is no root-to-leaf path with sum = 5.

Example 3:

Input: root = [], targetSum = 0
Output: false
Explanation: Since the tree is empty, there are no root-to-leaf paths.

 

Constraints:

  • The number of nodes in the tree is in the range [0, 5000].
  • -1000 <= Node.val <= 1000
  • -1000 <= targetSum <= 1000
Video Solution
Java Solution
				
					class Solution {
    public boolean hasPathSum(TreeNode root, int targetSum) {
        if(root == null){
            return false ;
        }
        if(root.left == null && root.right == null && root.val == targetSum){
            return true ;
        }
        boolean ans1 = hasPathSum(root.left , targetSum-root.val);
        boolean ans2 = hasPathSum(root.right, targetSum-root.val); 
        return ans1 || ans2 ;
    }
}
				
			

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