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[leetCode/JS] 938. Range Sum of BST 본문

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[leetCode/JS] 938. Range Sum of BST

쭘봉 2022. 12. 7. 09:42

난이도 [ 😊 ] Easy

 

문제 설명

Given the root node of a binary search tree and two integers low and high, return the sum of values of all nodes with a value in the inclusive range [low, high].

2진 트리의 노드 값이 low, high 범위에 들어오면 모두 더해서 return 한다. 

 

입출력 예

Example 1:

Input: root = [10,5,15,3,7,null,18], low = 7, high = 15
Output: 32
Explanation: Nodes 7, 10, and 15 are in the range [7, 15]. 7 + 10 + 15 = 32.

 

Example 2:

Input: root = [10,5,15,3,7,13,18,1,null,6], low = 6, high = 10
Output: 23
Explanation: Nodes 6, 7, and 10 are in the range [6, 10]. 6 + 7 + 10 = 23.

 

Constraints

  • The number of nodes in the tree is in the range [1, 2 * 104].
  • 1 <= Node.val <= 105
  • 1 <= low <= high <= 105
  • All Node.val are unique.

 


 

내 솔루션

  • 재귀함수로 기본적인 2진트리 탐색을 구현했다.
var rangeSumBST = function(root, low, high) {
  let sum = 0;
  const bst = (node) => {
    if(!node) return;
    if(low <= node.val && node.val <= high) sum += node.val
    bst(node.left)
    bst(node.right)
  }
  bst(root);
  return sum;
};

 

감상평

  • 딱 적당한 속도와 메모리. BST 호출 전에 if를 걸면 좀더 빨라질 수 있을까

 

 

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