[Swift Weekly Contest 117]LeetCode965. 單值二叉樹 | Univalued Binary Tree
阿新 • • 發佈:2018-12-31
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A binary tree is univalued if every node in the tree has the same value.
Return true
if and only if the given tree is univalued.
Example 1:
Input: [1,1,1,1,1,null,1]
Output: true
Example 2:
Input: [2,2,2,5,2]
Output: false
Note:
- The number of nodes in the given tree will be in the range
[1, 100]
- Each node‘s value will be an integer in the range
[0, 99]
.
如果二叉樹中的每個節點都具有相同的值,則二叉樹是單值的。
如果且僅當給定樹為單值時返回true。
例1:
輸入:[1,1,1,1,1,null,1]
輸出:真
例2:
輸入:[2,2,2,5,2]
輸出:假
註:
- 給定樹中的節點數將在範圍[1,100]內。
- 每個節點的值將是一個範圍[0,99]內的整數。
12 ms
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 var s:Set<Int> = Set<Int>()16 func isUnivalTree(_ root: TreeNode?) -> Bool { 17 s.insert(root!.val) 18 if root?.left != nil 19 { 20 isUnivalTree(root!.left) 21 } 22 if root?.right != nil 23 { 24 isUnivalTree(root!.right) 25 } 26 return s.count == 1 27 } 28 }
[Swift Weekly Contest 117]LeetCode965. 單值二叉樹 | Univalued Binary Tree