Path Sum Given the root
of a binary tree and an integer targetSum
, return true
if the tree has a root-to-leaf path such that adding up all the values along the path equals targetSum
.
A leaf is a node with no children.
Example 1:


Input: root = [5,4,8,11,null,13,4,7,2,null,null,null,1], targetSum = 22 Output: true Explanation: The root-to-leaf path with the target sum is shown.
Example 2:


Input: root = [1,2,3], targetSum = 5 Output: false Explanation: There two root-to-leaf paths in the tree: (1 --> 2): The sum is 3. (1 --> 3): The sum is 4. There is no root-to-leaf path with sum = 5.
Example 3:
Input: root = [], targetSum = 0 Output: false Explanation: Since the tree is empty, there are no root-to-leaf paths.
Constraints:
- The number of nodes in the tree is in the range
[0, 5000]
. -1000 <= Node.val <= 1000
-1000 <= targetSum <= 1000
Path Sum Solutions
✅Time: O(n)
✅Space: O(h)
C++
class Solution {
public:
bool hasPathSum(TreeNode* root, int sum) {
if (!root)
return false;
if (root->val == sum && !root->left && !root->right)
return true;
return hasPathSum(root->left, sum – root->val) ||
hasPathSum(root->right, sum – root->val);
}
};
Java
class Solution {
public boolean hasPathSum(TreeNode root, int sum) {
if (root == null)
return false;
if (root.val == sum && root.left == null && root.right == null)
return true;
return hasPathSum(root.left, sum - root.val) ||
hasPathSum(root.right, sum - root.val);
}
}
Python
class Solution:
def hasPathSum(self, root: TreeNode, sum: int) -> bool:
if not root:
return False
if root.val == sum and not root.left and not root.right:
return True
return self.hasPathSum(root.left, sum - root.val) or \
self.hasPathSum(root.right, sum - root.val)
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