112. Path Sum

Posted 2022-09-29 wentiliangkaihua

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

Note: A leaf is a node with no children.

Example:

Given the below binary tree and sum = 22,

      5
     /     4   8
   /   /   11  13  4
 /  \      7    2      1

return true, as there exist a root-to-leaf path 5->4->11->2 which sum is 22.

class Solution 
    public boolean hasPathSum(TreeNode root, int sum) 
        if(root == null) return false;
        if(root.left == null && root.right == null) return sum == root.val;
        return hasPathSum(root.left, sum - root.val) || hasPathSum(root.right, sum - root.val);
    

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