Java Clean Recursion Solution

  • 0

    Using one parameter boolean isLeft to check whether this leaf is on the left side.

    public class Solution {
        public int sumOfLeftLeaves(TreeNode root) {
            return helper(root, false);
        public int helper(TreeNode root, boolean isLeft) {
            if (root == null) return 0;
            if (root.left == null && root.right == null && isLeft) return root.val;
            return helper(root.left, true) + helper(root.right, false);

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