Path Sum
Path Sum
题目
Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.
For example:
Given the below binary tree and sum = 22,
5
/ \
4 8
/ / \
11 13 4
/ \ \
7 2 1
思路
结点左子树和右子树都为空，且该结点的值等于sum值，则返回真。
解题
c++版1
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19/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
bool hasPathSum(TreeNode* root, int sum) {
if(!root)
return false;
if(!root->left && !root->right && root->val==sum)
return true;
return hasPathSum(root->left,sum-root->val) || hasPathSum(root->right,sum-root->val);
}
};
python版
# Definition for a binary tree node
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
# @param root, a tree node
# @param sum, an integer
# @return a boolean
def hasPathSum(self, root, sum):
if not root:
return False
if (not root.left) and (not root .right) and (root.val==sum):
return True
else:
return self.hasPathSum(root.left,sum-root.val) or self.hasPathSum(root.right,sum-root.val)
