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LeetCode - 404. Sum of Left Leaves

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.

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

 

LeetCode - 404. Sum of Left Leaves