404. Sum of Left Leaves

class Solution(object): def sumOfLeftLeaves(self, root): """ :type root: TreeNode :rtype: int """ # def findleft(root): # if root: # if root.left != None: # self.sum += findleft(root.left) # if root.right != None: # self.sum += findleft(root.right) # if not root.left and not root.right: # return root.val # self.sum = 0 # findleft(root) # return self.sum if(root == None): return 0 ans = 0; if(root.left != None) : if root.left.left == None and root.left.right == None: ans += root.left.val; else: ans += self.sumOfLeftLeaves(root.left) ans += self.sumOfLeftLeaves(root.right) return ans;