Path Sum
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
return true, as there exist a root-to-leaf path 5->4->11->2
which sum is 22.
C++版
class Solution { public: bool hasPathSum(TreeNode *root, int sum) { if (root == NULL) return false; if (root->left == NULL && root->right == NULL && sum - root->val == 0) return true; return hasPathSum(root->left, sum - root->val) || hasPathSum(root->right, sum - root->val); } };
Java版本:
/** * Definition for binary tree * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public boolean hasPathSum(TreeNode root, int sum) { if (root == null) return false; if (root.left == null && root.right == null && sum - root.val == 0) return true; return hasPathSum(root.left, sum - root.val) || hasPathSum(root.right, sum - root.val); } }