[Swift]LeetCode938. 二叉搜索树的范围和 | Range Sum of BST

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Given the root node of a binary search tree, return the sum of values of all nodes with value between L and R (inclusive).

The binary search tree is guaranteed to have unique values.

Example 1:

Input: root = [10,5,15,3,7,null,18], L = 7, R = 15
Output: 32

Example 2:

Input: root = [10,5,15,3,7,13,18,1,null,6], L = 6, R = 10
Output: 23

Note:

1. The number of nodes in the tree is at most 10000.
2. The final answer is guaranteed to be less than 2^31.

---

给定二叉搜索树的根结点 root，返回 L 和 R（含）之间的所有结点的值的和。

二叉搜索树保证具有唯一的值。 

示例 1：

输入：root = [10,5,15,3,7,null,18], L = 7, R = 15
输出：32

示例 2：

输入：root = [10,5,15,3,7,13,18,1,null,6], L = 6, R = 10
输出：23

提示：

1. 树中的结点数量最多为 10000 个。
2. 最终的答案保证小于 2^31。

---

616ms

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public var val: Int
 *     public var left: TreeNode?
 *     public var right: TreeNode?
 *     public init(_ val: Int) {
 *         self.val = val
 *         self.left = nil
 *         self.right = nil
 *     }
 * }
 */
class Solution {
    func rangeSumBST(_ root: TreeNode?, _ L: Int, _ R: Int) -> Int {
        var sum = 0
        _rangeSumBST(root, L, R, &sum)
        return sum
    }
    
    func _rangeSumBST(_ root: TreeNode?, _ low: Int, _ high: Int, _ sum: inout Int) {
        guard let root = root else { return }
        if root.val >= low && root.val <= high {
            sum += root.val
        }
        if root.val > low {
            _rangeSumBST(root.left, low, high, &sum)
        }
        if root.val < high {
            _rangeSumBST(root.right, low, high, &sum)
        }
    }
}

---

628ms

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public var val: Int
 *     public var left: TreeNode?
 *     public var right: TreeNode?
 *     public init(_ val: Int) {
 *         self.val = val
 *         self.left = nil
 *         self.right = nil
 *     }
 * }
 */
class Solution {
    func rangeSumBST(_ rt: TreeNode?, _ L: Int, _ R: Int) -> Int {
      var sum = 0  
      if let root = rt {
        if root.val >= L && root.val <= R { sum += root.val }
        sum += rangeSumBST(root.left, L, R)
        sum += rangeSumBST(root.right, L, R)
      }
      return sum
    }
}

---

632ms

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public var val: Int
 *     public var left: TreeNode?
 *     public var right: TreeNode?
 *     public init(_ val: Int) {
 *         self.val = val
 *         self.left = nil
 *         self.right = nil
 *     }
 * }
 */ 
class Solution {
    func rangeSumBST(_ root: TreeNode?, _ L: Int, _ R: Int) -> Int {
        
        guard let r = root else {
            return 0
        }
        
        if r.val < L {
            return rangeSumBST(r.right, L, R)
        } else if r.val > R {
            return rangeSumBST(r.left, L, R)
        } else {
            return r.val + rangeSumBST(r.left, L, R) + rangeSumBST(r.right, L, R)
        }
    }
}

---

652ms

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public var val: Int
 *     public var left: TreeNode?
 *     public var right: TreeNode?
 *     public init(_ val: Int) {
 *         self.val = val
 *         self.left = nil
 *         self.right = nil
 *     }
 * }
 */
class Solution{
        var sum = 0;
        func rangeSumBST(_ root: TreeNode?, _ L: Int, _ R: Int) -> Int {
            sum = 0;
            traverse(root, L, R)
            return sum;
        }
        func traverse(_ root:TreeNode?, _ L:Int,_ R:Int) -> Void {
            if(root != nil)
            {
                if(L <= root!.val && R >= root!.val)
                {
                    sum += root!.val;
                }
                traverse(root!.left, L, R);
                traverse(root!.right, L, R);
            }
        }
    }

---

656ms

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public var val: Int
 *     public var left: TreeNode?
 *     public var right: TreeNode?
 *     public init(_ val: Int) {
 *         self.val = val
 *         self.left = nil
 *         self.right = nil
 *     }
 * }
 */
class Solution {
    func rangeSumBST(_ root: TreeNode?, _ L: Int, _ R: Int) -> Int {
        return dfs(root,L,R)
    }
    
    func dfs(_ root: TreeNode?, _ L: Int, _ R: Int) -> Int
    {
        if root == nil {return 0}
        return dfs(root!.left, L, R) + dfs(root!.right, L, R) + (L <= root!.val && root!.val <= R ? root!.val : 0)
    }
}

---

672ms

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public var val: Int
 *     public var left: TreeNode?
 *     public var right: TreeNode?
 *     public init(_ val: Int) {
 *         self.val = val
 *         self.left = nil
 *         self.right = nil
 *     }
 * }
 */
class Solution {
    func rangeSumBST(_ root: TreeNode?, _ L: Int, _ R: Int) -> Int {
        if (root == nil) {
            return 0;
        }
        if (root!.val < L) {
            return rangeSumBST(root!.right, L, R)
        }
        if (root!.val > R) {
            return rangeSumBST(root!.left, L, R)
        }
        return root!.val + rangeSumBST(root!.left, L, R) + rangeSumBST(root!.right, L, R)
    }
}