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112. Path Sum 👍

  • Time: $O(n)$
  • Space: $O(h)$
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class Solution {
 public:
  bool hasPathSum(TreeNode* root, int sum) {
    if (root == nullptr)
      return false;
    if (root->val == sum && root->left == nullptr && root->right == nullptr)
      return true;
    return hasPathSum(root->left, sum - root->val) ||
           hasPathSum(root->right, sum - root->val);
  }
};

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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);
  }
}

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class Solution:
  def hasPathSum(self, root: TreeNode, summ: int) -> bool:
    if not root:
      return False
    if root.val == summ and not root.left and not root.right:
      return True
    return (self.hasPathSum(root.left, summ - root.val) or
            self.hasPathSum(root.right, summ - root.val))