[Swift]LeetCode515. 在每个树行中找最大值 | Find Largest Value in Each Tree Row
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You need to find the largest value in each row of a binary tree.
Example:
Input:
1
/ \
3 2
/ \ \
5 3 9
Output: [1, 3, 9]
您需要在二叉树的每一行中找到最大的值。
示例：
输入:
1
/ \
3 2
/ \ \
5 3 9
输出: [1, 3, 9]
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 largestValues(_ root: TreeNode?) -> [Int] { 16 guard let rootNode = root else { 17 return [] 18 } 19 var result: [Int] = [] 20 var originallist: [TreeNode] = [rootNode] 21 22 while !originallist.isEmpty { 23 var tempList: [TreeNode] = originallist 24 originallist.removeAll() 25 var tempvalue: Int = Int.min 26 for var node: TreeNode in tempList { 27 tempvalue = max(tempvalue,node.val) 28 if let left: TreeNode = node.left { 29 originallist.append(left) 30 } 31 if let right: TreeNode = node.right { 32 originallist.append(right) 33 } 34 } 35 result.append(tempvalue) 36 } 37 return result 38 } 39 }
56ms
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 largestValues(_ root: TreeNode?) -> [Int] { 16 guard let root = root else { 17 return [] 18 } 19 var maxVals: [Int] = [root.val] 20 getMaxValues(root, 0, &maxVals) 21 return maxVals 22 } 23 24 func getMaxValues(_ root: TreeNode, _ currentLevel: Int, _ maxVals: inout [Int]) { 25 if maxVals.count > currentLevel { 26 if root.val > maxVals[currentLevel] { 27 maxVals[currentLevel] = root.val 28 } 29 } else { 30 maxVals.append(root.val) 31 } 32 33 if let left = root.left { 34 getMaxValues(left, currentLevel + 1, &maxVals) 35 } 36 if let right = root.right { 37 getMaxValues(right, currentLevel + 1, &maxVals) 38 } 39 } 40 }
Runtime: 60 ms
Memory Usage: 20.3 MB
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 largestValues(_ root: TreeNode?) -> [Int] { 16 if root == nil {return []} 17 var res:[Int] = [Int]() 18 helper(root,1,&res) 19 return res 20 } 21 22 func helper(_ root: TreeNode?,_ depth:Int,_ res:inout [Int]) 23 { 24 if depth > res.count {res.append(root!.val)} 25 else {res[depth - 1] = max(res[depth - 1], root!.val)} 26 if root!.left != nil {helper(root!.left, depth + 1, &res)} 27 if root!.right != nil {helper(root!.right, depth + 1, &res)} 28 } 29 }
68ms
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 largestValues(_ root: TreeNode?) -> [Int] { 16 if root == nil { 17 return [] 18 } 19 var maxVal = Int.min 20 var maxArray = [Int]() 21 var queue = [TreeNode?]() 22 queue.append(root) 23 queue.append(nil) 24 25 while !queue.isEmpty { 26 var node = queue.removeFirst() 27 if node == nil { 28 maxArray.append(maxVal) 29 maxVal = Int.min 30 if !queue.isEmpty { 31 queue.append(nil) 32 } 33 } else { 34 maxVal = max(maxVal, node?.val ?? 0) 35 if node?.left != nil { 36 queue.append(node?.left) 37 } 38 39 if node?.right != nil { 40 queue.append(node?.right) 41 } 42 } 43 } 44 return maxArray 45 } 46 }
72ms
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 largestValues(_ root: TreeNode?) -> [Int] { 16 guard let root = root else { return [] } 17 var queue = [TreeNode]() 18 queue.append(root) 19 var result = [root.val] 20 while !queue.isEmpty { 21 var maximum = Int.min 22 var tmpQueue = [TreeNode]() 23 while !queue.isEmpty { 24 let node = queue[0] 25 queue.removeFirst() 26 if let left = node.left { 27 tmpQueue.append(left) 28 maximum = max(maximum, left.val) 29 } 30 if let right = node.right { 31 tmpQueue.append(right) 32 maximum = max(maximum, right.val) 33 } 34 35 } 36 if !tmpQueue.isEmpty { 37 result.append(maximum) 38 } 39 queue = tmpQueue 40 } 41 return result 42 } 43 }
76ms
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 largestValues(_ root: TreeNode?) -> [Int] { 16 var q = [TreeNode?]() 17 var remainingNodesInLevel = 0 18 var maxNums = [Int]() 19 q.append(root) 20 while q.count > 0 { 21 remainingNodesInLevel = q.count 22 var levelNodeValues = [Int]() 23 while remainingNodesInLevel > 0 { 24 guard let peek = q.first else { break } 25 q.removeFirst() 26 if let p = peek { 27 levelNodeValues.append(p.val) 28 if p.left != nil { q.append(p.left) } 29 if p.right != nil { q.append(p.right) } 30 remainingNodesInLevel -= 1 31 } else { 32 break 33 } 34 } 35 levelNodeValues = levelNodeValues.sorted {$0 > $1} 36 if let max = levelNodeValues.first { 37 maxNums.append(max) 38 } 39 } 40 return maxNums 41 } 42 }
128ms
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 largestValues(_ root: TreeNode?) -> [Int] { 16 if root == nil { 17 return [Int]() 18 } 19 var queue = [(TreeNode, Int)]() 20 var result = [Int]() 21 queue.append((root!, 0)) 22 while queue.count > 0 { 23 let set = queue.removeFirst() 24 if result.count <= set.1 { 25 result.append(set.0.val) 26 } else { 27 result[set.1] = max(result[set.1], set.0.val) 28 } 29 if set.0.left != nil { 30 queue.append((set.0.left!, set.1 + 1)) 31 } 32 if set.0.right != nil { 33 queue.append((set.0.right!, set.1 + 1)) 34 } 35 } 36 return result 37 } 38 }
