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. # class TreeNode(object): # def __init__(self, x): # self.val = x # self.left = None # self.right = None class Solution(object): def sumOfLeftLeaves(self, root): """ :type root: TreeNode :rtype: int """ # Recursion method ‘‘‘ def rer(node,left): if not node: return 0 if left: if node.left or node.right: return rer(node.left,True)+rer(node.right,False) else: return node.val else: return rer(node.right,False)+rer(node.left,True) return rer(root,False) ‘‘‘ # Non-recursion method ans=0 if root: stack=[root] while stack: node=stack.pop() if node.left: if not node.left.left and not node.left.right: ans+=node.left.val else: stack.append(node.left) if node.right: stack.append(node.right) return ans
原文地址:https://www.cnblogs.com/chiyeung/p/10053015.html
时间: 2024-10-16 13:32:32