LeetCode@Tree_404_Sum_of_Left_Leaves

404. Sum of Left Leaves

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Find the sum of all left leaves in a given binary tree.

Example:

    3   / \  9  20    /  \   15   7There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24.

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java:

/** * Definition for a binary tree node. * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {  public int sumOfLeftLeaves(TreeNode root){int sum = 0;if (root == null)return 0;if (root.left != null){if (root.left.left == null && root.left.right == null){sum += root.left.val;}}return sum + sumOfLeftLeaves(root.left) + sumOfLeftLeaves(root.right);}}