404. Sum of Left Leaves #
题目 #
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.
题目大意 #
计算给定二叉树的所有左叶子之和。
解题思路 #
- 这一题是微软的面试题。递归求解即可
代码 #
package leetcode
/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
func sumOfLeftLeaves(root *TreeNode) int {
if root == nil {
return 0
}
if root.Left != nil && root.Left.Left == nil && root.Left.Right == nil {
return root.Left.Val + sumOfLeftLeaves(root.Right)
}
return sumOfLeftLeaves(root.Left) + sumOfLeftLeaves(root.Right)
}