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delight010.swift
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41 lines (33 loc) · 1019 Bytes
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public class TreeNode {
public var val: Int
public var left: TreeNode?
public var right: TreeNode?
public init() { self.val = 0; self.left = nil; self.right = nil; }
public init( val: Int) { self.val = val; self.left = nil; self.right = nil; }
public init( val: Int, * left: TreeNode?, * right: TreeNode?) {
self.val = val
self.left = left
self.right = right
}
}
class Solution {
// Time O(n)
// Space O(n)
func invertTree(_ root: TreeNode?) -> TreeNode? {
guard let root = root else {
return nil
}
var queue: [TreeNode] = [root]
while queue.isEmpty == false {
let current = queue.removeFirst()
if let left = current.left {
queue.append(left)
}
if let right = current.right {
queue.append(right)
}
(current.left, current.right) = (current.right, current.left)
}
return root
}
}