Sum of left leaves

SumOfLeftLeaves.java

package com.interviewbytes.trees;

public class SumOfLeftLeaves {

    public int sumOfLeftLeaves(TreeNode root) {

        if (root == null) return 0;

        int sum = 0;

        if (root.left != null && root.left.left == null && root.left.right == null) sum = sum + root.left.val;

        sum = sum + sumOfLeftLeaves(root.left);
        sum = sum + sumOfLeftLeaves(root.right);

        return sum;
    }
}

TreeNode.java

package com.interviewbytes.trees;

public class TreeNode {

    int val;
    TreeNode left;
    TreeNode right;

    TreeNode(int x) {
        val = x;
    }
}