LeetCode之Sum of Left Leaves

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

Example:

        3
          / \
         9  20
        /  \
          15   7
       There 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 {
        public int sumOfLeftLeaves(TreeNode head) {
        if (head == null) return 0;
       		int left = 0, right = 0;
       		if (head.left != null && head.left.left == null && head.left.right == null) {
       			left = head.left.val;
       		} else {
       			left = sumOfLeftLeaves(head.left);
       		}
       		right = sumOfLeftLeaves(head.right);
       		return left + right;
        }
       }