BinaryTree

README.md

@@ -16,34 +16,42 @@ swift run LeetCode_ addDigits
 
 ## Solved
 
-- [581. Shortest Unsorted Continuous Subarray](https://leetcode.com/problems/shortest-unsorted-continuous-subarray/) · [Submission](Sources/LeetCode_/581.ShortestUnsortedContinuousSubarray/ShortestUnsortedContinuousSubarray.swift)
+- [581. Shortest Unsorted Continuous Subarray](https://leetcode.com/problems/shortest-unsorted-continuous-subarray/) · [Submission](Sources/LeetCode_/LeetCode/581.ShortestUnsortedContinuousSubarray/ShortestUnsortedContinuousSubarray.swift)
 
-- [258. Add Digits](https://leetcode.com/problems/add-digits/) · [Submission](Sources/LeetCode_/258.AddDigits/AddDigits.swift)
+- [258. Add Digits](https://leetcode.com/problems/add-digits/) · [Submission](Sources/LeetCode_/LeetCode/258.AddDigits/AddDigits.swift)
 
-- [453. Minimum Moves to Equal Array Elements](https://leetcode.com/problems/minimum-moves-to-equal-array-elements/) · [Submission](Sources/LeetCode_/453.MinimumMovesToEqualArrayElements/MinimumMovesToEqual.swift)
+- [453. Minimum Moves to Equal Array Elements](https://leetcode.com/problems/minimum-moves-to-equal-array-elements/) · [Submission](Sources/LeetCode_/LeetCode/453.MinimumMovesToEqualArrayElements/MinimumMovesToEqual.swift)
 
-- [665. Non-decreasing Array](https://leetcode.com/problems/non-decreasing-array/) · [Submission](Sources/LeetCode_/665.Non-decreasingArray/NonDecreasing.swift)
+- [665. Non-decreasing Array](https://leetcode.com/problems/non-decreasing-array/) · [Submission](Sources/LeetCode_/LeetCode/665.Non-decreasingArray/NonDecreasing.swift)
 
-- [125. Valid Palindrome](https://leetcode.com/problems/valid-palindrome/) · [Submission](Sources/LeetCode_/125.ValidPalindrome/ValidPalindrome.swift)
+- [125. Valid Palindrome](https://leetcode.com/problems/valid-palindrome/) · [Submission](Sources/LeetCode_/LeetCode/125.ValidPalindrome/ValidPalindrome.swift)
 
-- [832. Flipping an Image](https://leetcode.com/problems/flipping-an-image/) · [Submission](Sources/LeetCode_/832.FlippingAnImage/FlippingAnImage.swift)
+- [832. Flipping an Image](https://leetcode.com/problems/flipping-an-image/) · [Submission](Sources/LeetCode_/LeetCode/832.FlippingAnImage/FlippingAnImage.swift)
 
-- [628. Maximum Product of Three Numbers](https://leetcode.com/problems/maximum-product-of-three-numbers/) · [Submission](Sources/LeetCode_/628.MaximumProductOfThreeNumbers/MaximumProductOfThreeNumbers.swift)
+- [628. Maximum Product of Three Numbers](https://leetcode.com/problems/maximum-product-of-three-numbers/) · [Submission](Sources/LeetCode_/LeetCode/628.MaximumProductOfThreeNumbers/MaximumProductOfThreeNumbers.swift)
 
-- [575. Distribute Candies](https://leetcode.com/problems/distribute-candies/) · [Submission](Sources/LeetCode_/575.DistributeCandies/DistributeCandies.swift)
+- [575. Distribute Candies](https://leetcode.com/problems/distribute-candies/) · [Submission](Sources/LeetCode_/LeetCode/575.DistributeCandies/DistributeCandies.swift)
 
-- [872. Leaf-Similar Trees](https://leetcode.com/problems/leaf-similar-trees/) · [Submission](Sources/LeetCode_/872.Leaf-SimilarTrees/Leaf-SimilarTrees.swift)
+- [872. Leaf-Similar Trees](https://leetcode.com/problems/leaf-similar-trees/) · [Submission](Sources/LeetCode_/LeetCode/872.Leaf-SimilarTrees/Leaf-SimilarTrees.swift)
 
-- [495. Teemo Attacking](https://leetcode.com/problems/teemo-attacking/) · [Submission](Sources/LeetCode_/495.TeemoAttacking/TeemoAttacking.swift)
+- [495. Teemo Attacking](https://leetcode.com/problems/teemo-attacking/) · [Submission](Sources/LeetCode_/LeetCode/495.TeemoAttacking/TeemoAttacking.swift)
 
-- [088. Merge Sorted Array](https://leetcode-cn.com/problems/merge-sorted-array/) · [Submission](Sources/LeetCode_/088.MergeSortedArray/MergeSortedArray.swift)
+- [088. Merge Sorted Array](https://leetcode-cn.com/problems/merge-sorted-array/) · [Submission](Sources/LeetCode_/LeetCode/088.MergeSortedArray/MergeSortedArray.swift)
 
-- [209. Minimum Size Subarray Sum](https://leetcode.com/problems/minimum-size-subarray-sum/) · [Submission](Sources/LeetCode_/209.MinimumSizeSubarraySum/MinimumSizeSubarraySum.swift)
+- [209. Minimum Size Subarray Sum](https://leetcode.com/problems/minimum-size-subarray-sum/) · [Submission](Sources/LeetCode_/LeetCode/209.MinimumSizeSubarraySum/MinimumSizeSubarraySum.swift)
 
-- [014. Longest Common Prefix](https://leetcode.com/problems/longest-common-prefix/) · [Submission](Sources/LeetCode_/014.LongestCommonPrefix/LongestCommonPrefix.swift)
+- [014. Longest Common Prefix](https://leetcode.com/problems/longest-common-prefix/) · [Submission](Sources/LeetCode_/LeetCode/014.LongestCommonPrefix/LongestCommonPrefix.swift)
 
-- [881. Boats to Save People](https://leetcode.com/problems/boats-to-save-people/) · [Submission](Sources/LeetCode_/881.BoatstoSavePeople/BoatstoSavePeople.swift)
+- [881. Boats to Save People](https://leetcode.com/problems/boats-to-save-people/) · [Submission](Sources/LeetCode_/LeetCode/881.BoatstoSavePeople/BoatstoSavePeople.swift)
+
+- [376. Wiggle Subsequence](https://leetcode.com/problems/wiggle-subsequence/) · [Submission](Sources/LeetCode_/LeetCode/376.WiggleSubsequence/WiggleSubsequence.swift)
+
+- [229. Majority Element II](https://leetcode.com/problems/majority-element-ii/) · [Submission](Sources/LeetCode_/LeetCode/229.MajorityElementII/MajorityElementII.swift)
+
+## 
+
+- [Binary Tree](Sources/LeetCode_/BinaryTree/BinaryTree.swift)
+
+- [Binary Search Tree](Sources/LeetCode_/BinaryTree/BinarySearchTree.swift)
 
-- [376. Wiggle Subsequence](https://leetcode.com/problems/wiggle-subsequence/) · [Submission](Sources/LeetCode_/376.WiggleSubsequence/WiggleSubsequence.swift)
 
-- [229. Majority Element II](https://leetcode.com/problems/majority-element-ii/) · [Submission](Sources/LeetCode_/229.MajorityElementII/MajorityElementII.swift)

Sources/LeetCode_/BinaryTree/BinarySearchTree.swift

@@ -0,0 +1,167 @@
+//
+//  File.swift
+//  
+//
+//  Created by 韩元旭 on 2020/6/9.
+//
+
+import Foundation
+
+// MARK: - 修剪二叉搜索树
+/// https://leetcode-cn.com/problems/trim-a-binary-search-tree/
+extension Solution {
+
+    // 给定一个二叉搜索树，同时给定最小边界L 和最大边界 R。通过修剪二叉搜索树，使得所有节点的值在[L, R]中 (R>=L)
+
+    /// 修剪二叉搜索树
+    func trimBST(_ root: TreeNode?, _ L: Int, _ R: Int) -> TreeNode? {
+        guard let tree = root else { return nil }
+        if tree.val > R {
+            return trimBST(tree.left, L, R)
+        }
+        if tree.val < L {
+            return trimBST(tree.right, L, R)
+        }
+        tree.left = trimBST(tree.left, L, R)
+        tree.right = trimBST(tree.right, L, R)
+        return tree
+    }
+
+}
+
+// MARK: - 把二叉搜索树转换为累加树
+/// https://leetcode-cn.com/problems/convert-bst-to-greater-tree/
+extension Solution {
+
+    // 使得每个节点的值是原来的节点值加上所有大于它的节点值之和。
+
+    /// 把二叉搜索树转换为累加树 - 反序中序遍历
+    func convertBST(_ root: TreeNode?) -> TreeNode? {
+        var sum: Int = 0
+
+        func rec(_ root: TreeNode?) {
+            guard let tree = root else { return }
+            rec(tree.right)
+            sum += tree.val
+            tree.val = sum
+            rec(tree.left)
+        }
+
+        rec(root)
+        return root
+    }
+
+    #warning("TODO LeetCode 上还有两种方法")
+
+}
+
+
+// MARK: - 二叉搜索树中的搜索
+/// https://leetcode-cn.com/problems/search-in-a-binary-search-tree/
+extension Solution {
+
+    // 返回以该节点为根的子树。 如果节点不存在，则返回 NULL
+
+    /// 二叉搜索树中的搜索
+    func searchBST(_ root: TreeNode?, _ val: Int) -> TreeNode? {
+        guard let tree = root else { return nil }
+        if val == tree.val {
+            return tree
+        } else if val > tree.val {
+            return searchBST(tree.right, val)
+        } else {
+            return searchBST(tree.left, val)
+        }
+    }
+
+    /// 二叉搜索树中的搜索 - 迭代
+    func searchBST_BFS(_ root: TreeNode?, _ val: Int) -> TreeNode? {
+        var tree = root
+        while tree != nil && tree?.val != val {
+            tree = tree!.val > val ? tree?.left : tree?.right
+        }
+        return tree
+    }
+
+}
+
+
+// MARK: - 二叉搜索树的范围和
+/// https://leetcode-cn.com/problems/range-sum-of-bst/
+extension Solution {
+
+    // 返回 L 和 R（含）之间的所有结点的值的和
+
+    /// 二叉搜索树的范围和
+    func rangeSumBST(_ root: TreeNode?, _ L: Int, _ R: Int) -> Int {
+        var sum = 0
+
+        func rec(_ root: TreeNode?) {
+            guard let tree = root else { return }
+            if  L <= tree.val && tree.val <= R{
+                sum += tree.val
+            }
+
+            if L < tree.val {
+                rec(tree.left)
+            }
+
+            if tree.val < R {
+                rec(tree.right)
+            }
+        }
+
+        rec(root)
+        return sum
+    }
+
+    /// 二叉搜索树的范围和
+    func rangeSumBST_BFS(_ root: TreeNode?, _ L: Int, _ R: Int) -> Int {
+        guard let tree = root else { return 0 }
+        var sum = 0
+        var stack = [tree]
+        while !stack.isEmpty {
+            guard let node = stack.popLast() else { break }
+            if  L <= node.val && node.val <= R{
+                sum += node.val
+            }
+
+            if let left = node.left, L < node.val {
+                stack.append(left)
+            }
+
+            if let right = node.right, node.val < R {
+                stack.append(right)
+            }
+        }
+        return sum
+    }
+
+}
+
+// MARK: -  二叉搜索树的第k大节点
+/// https://leetcode-cn.com/problems/er-cha-sou-suo-shu-de-di-kda-jie-dian-lcof/
+extension Solution {
+
+    // Tips 中序遍历是递增序列
+    // 根据以上性质，易得二叉搜索树的“中序遍历倒序”为 递减序列 。
+
+    // 二叉搜索树的第k大节点
+    func kthLargest(_ root: TreeNode?, _ k: Int) -> Int {
+        var value = -1
+        var count = k
+
+        func rec(_ root: TreeNode?) {
+            guard let tree = root else { return }
+            rec(tree.right)
+            if count == 0 { return }
+            count -= 1
+            if count == 0 { value = tree.val }
+            rec(tree.left)
+        }
+
+        rec(root)
+        return value
+    }
+
+}