404. 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.

 1 class Solution {
 2     
 3     public int sumOfLeftLeaves(TreeNode root) {
 4         if(root==null) return 0;
 5         int sum = 0;
 6         if(root.left!=null){
 7             if(root.left.left==null && root.left.right==null) sum +=root.left.val;
 8             else sum+=sumOfLeftLeaves(root.left);
 9         }
10         sum+=sumOfLeftLeaves(root.right);
11         return sum;
12         
13     }
14  
15 }

 

posted @ 2017-11-01 22:02  乐乐章  阅读(101)  评论(0)  编辑  收藏  举报