[Swift]LeetCode530. 二叉搜索树的最小绝对差 | Minimum Absolute Difference in BST
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Given a binary search tree with non-negative values, find the minimum absolute difference between values of any two nodes.
Example:
Input:
1
\
3
/
2
Output:
1
Explanation:
The minimum absolute difference is 1, which is the difference between 2 and 1 (or between 2 and 3).
Note: There are at least two nodes in this BST.
给定一个所有节点为非负值的二叉搜索树，求树中任意两节点的差的绝对值的最小值。
示例 :
输入:
1
\
3
/
2
输出:
1
解释:
最小绝对差为1，其中 2 和 1 的差的绝对值为 1（或者 2 和 3）。
注意: 树中至少有2个节点。
44ms
1 /** 2 * Definition for a binary tree node. 3 * public class TreeNode { 4 * public var val: Int 5 * public var left: TreeNode? 6 * public var right: TreeNode? 7 * public init(_ val: Int) { 8 * self.val = val 9 * self.left = nil 10 * self.right = nil 11 * } 12 * } 13 */ 14 class Solution { 15 private var array = [Int]() 16 func getMinimumDifference(_ root: TreeNode?) -> Int { 17 inOrder(root) 18 19 var minDiff = Int.max 20 21 for x in 0..<array.count-1 { 22 let diff = array[x+1] - array[x] 23 if diff < minDiff { 24 minDiff = diff 25 } 26 } 27 28 return minDiff 29 } 30 31 private func inOrder(_ node: TreeNode?) { 32 guard let node = node else { return } 33 inOrder(node.left) 34 array.append(node.val) 35 inOrder(node.right) 36 } 37 }
48ms
1 /** 2 * Definition for a binary tree node. 3 * public class TreeNode { 4 * public var val: Int 5 * public var left: TreeNode? 6 * public var right: TreeNode? 7 * public init(_ val: Int) { 8 * self.val = val 9 * self.left = nil 10 * self.right = nil 11 * } 12 * } 13 */ 14 class Solution { 15 func getMinimumDifference(_ root: TreeNode?) -> Int { 16 var res = Int.max 17 guard let root = root else { return res } 18 19 if var left = root.left { 20 while left.right != nil { 21 left = left.right! 22 } 23 let diff = abs(left.val - root.val) 24 if res > diff { res = diff } 25 } 26 27 if var right = root.right { 28 while right.left != nil { 29 right = right.left! 30 } 31 let diff = abs(root.val - right.val) 32 if res > diff { res = diff } 33 } 34 35 let minLeft = getMinimumDifference(root.left) 36 if res > minLeft { res = minLeft } 37 let minRight = getMinimumDifference(root.right) 38 if res > minRight { res = minRight } 39 40 return res 41 } 42 }
52ms
1 /** 2 * Definition for a binary tree node. 3 * public class TreeNode { 4 * public var val: Int 5 * public var left: TreeNode? 6 * public var right: TreeNode? 7 * public init(_ val: Int) { 8 * self.val = val 9 * self.left = nil 10 * self.right = nil 11 * } 12 * } 13 */ 14 class Solution { 15 16 func getMinimumDifference(_ root: TreeNode?) -> Int { 17 var pre: Int? 18 return getMinimumDifference(root, &pre) 19 } 20 21 func getMinimumDifference(_ root: TreeNode?, _ val: inout Int?) -> Int { 22 guard let root = root else { 23 return Int.max 24 } 25 26 var result = getMinimumDifference(root.left, &val) 27 if let val = val { 28 result = min(result, root.val - val) 29 } 30 31 val = root.val 32 33 result = min(result, getMinimumDifference(root.right, &val)) 34 35 return result 36 } 37 38 }
64ms
1 /** 2 * Definition for a binary tree node. 3 * public class TreeNode { 4 * public var val: Int 5 * public var left: TreeNode? 6 * public var right: TreeNode? 7 * public init(_ val: Int) { 8 * self.val = val 9 * self.left = nil 10 * self.right = nil 11 * } 12 * } 13 */ 14 class Solution { 15 func getMinimumDifference(_ root: TreeNode?) -> Int { 16 var result = Int.max 17 var pre: Int? 18 let a = getMinimumDifference(root, &pre, &result) 19 print(a) 20 return result 21 } 22 23 func getMinimumDifference(_ root: TreeNode?, _ val: inout Int?, _ result: inout Int) -> Int { 24 guard let root = root else { 25 return result 26 } 27 28 getMinimumDifference(root.left, &val, &result) 29 if let val = val { 30 result = min(result, root.val - val) 31 } 32 33 val = root.val 34 getMinimumDifference(root.right, &val, &result) 35 36 return result 37 } 38 }
92ms
1 /** 2 * Definition for a binary tree node. 3 * public class TreeNode { 4 * public var val: Int 5 * public var left: TreeNode? 6 * public var right: TreeNode? 7 * public init(_ val: Int) { 8 * self.val = val 9 * self.left = nil 10 * self.right = nil 11 * } 12 * } 13 */ 14 class Solution { 15 func getMinimumDifference(_ root: TreeNode?) -> Int { 16 var set = Set<Int>.init() 17 var queue = [TreeNode]() 18 if let node = root { 19 queue.append(node) 20 } 21 while !queue.isEmpty { 22 let node = queue.first 23 queue.removeFirst() 24 set.update(with: node!.val) 25 if node!.left != nil { 26 queue.append(node!.left!) 27 } 28 if node!.right != nil { 29 queue.append(node!.right!) 30 } 31 } 32 var res = Int.max 33 let arr = set.sorted() 34 for i in 0..<arr.count-1 { 35 if abs(arr[i]-arr[i+1]) < res { 36 res = abs(arr[i]-arr[i+1]) 37 } 38 } 39 return res 40 } 41 }
92ms
1 /** 2 * Definition for a binary tree node. 3 * public class TreeNode { 4 * public var val: Int 5 * public var left: TreeNode? 6 * public var right: TreeNode? 7 * public init(_ val: Int) { 8 * self.val = val 9 * self.left = nil 10 * self.right = nil 11 * } 12 * } 13 */ 14 class Solution { 15 func getMinimumDifference(_ root: TreeNode?) -> Int { 16 //中序遍历的递归方法 17 var res:Int = Int.max, pre:Int = -1 18 inOrder(root,&pre ,&res) 19 return res 20 } 21 func inOrder(_ root: TreeNode?,_ pre: inout Int,_ res: inout Int) 22 { 23 if root == nil {return} 24 inOrder(root!.left,&pre,&res) 25 if pre != -1 26 { 27 res = min(res,root!.val - pre) 28 } 29 pre = root!.val 30 inOrder(root!.right,&pre,&res) 31 } 32 }
