{1,2,3}25
{1,0}10
{1,2,0,3,4}257
# class TreeNode: # def __init__(self, x): # self.val = x # self.left = None # self.right = None # # # @param root TreeNode类 # @return int整型 # class Solution: def sumNumbers(self , root ): # write code here if not root: return 0 res = [] def dfs(root,temp): if not root: return if not root.left and not root.right: temp += str(root.val) res.append(temp) dfs(root.left, temp+str(root.val)) dfs(root.right, temp+str(root.val)) return dfs(root, "") sum_ = 0 for i in res: sum_ += int(i) return sum_根据路径和总结的经验
s = '' count = 0 class Solution: def get(self,root): global count , s if(root): s+=str(root.val) if not root.left and not root.right: count+=int(s) s = s[:-1] if root.left: self.get(root.left) if root.right: self.get(root.right) def sumNumbers(self , root ): # write code here if not root: return 0 self.get(root) return count{0,1} 这组数据测试没问题，提交就出错。懵了？？？？？？？？？？？？？？？？
class Solution: def sumNumbers(self , root ): ret = 0 cur = 0 last = None stack=[] while root or stack: if root: stack.append(root) cur = cur * 10 + root.val root = root.left else: root = stack[-1] root = root.right if root is None or root == last: root = stack.pop(-1) if not root.left and not root.right: ret += cur cur = cur/10 last = root root = None
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public int sumNumbers(TreeNode root) { int sum = 0; if (root == null) { return sum; } return preorderSumNumbers(root, sum); } public int preorderSumNumbers(TreeNode root, int sum) { if (root == null) return 0; sum = sum * 10 + root.val; if (root.left == null && root.right == null) { return sum; } return preorderSumNumbers(root.left, sum) + preorderSumNumbers(root.right, sum); }