problems:
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.
Note: A leaf is a node with no children.
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.
solution:
class Solution {
public:
bool hasPathSum(TreeNode* root, int sum) {
if(!root) return false;//空节点的情况
if(!root->left && !root->right) //只有根节点的情况
{
if(root->val != sum)
return false;
else
return true;
}
bool a=hasPathSum(root->left,sum-root->val);
bool b=hasPathSum(root->right,sum-root->val);
if(a || b) return true;
else return false;
}
};