LeetCode: 100. Same Tree

https://leetcode.com/problems/same-tree/description/

 

Given the roots of two binary trees p and q, write a function to check if they are the same or not.

Two binary trees are considered the same if they are structurally identical, and the nodes have the same value.

 

Example 1:

Input: p = [1,2,3], q = [1,2,3]
Output: true

Example 2:

Input: p = [1,2], q = [1,null,2]
Output: false

Example 3:

Input: p = [1,2,1], q = [1,1,2]
Output: false
 

Constraints:

The number of nodes in both trees is in the range [0, 100].
-104 <= Node.val <= 104

 

풀이

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 {
    func isSameTree(_ p: TreeNode?, _ q: TreeNode?) -> Bool {
        guard p != nil || q != nil else { return true }
        guard let p = p, let q = q else { return false }
        
        return p.val == q.val && isSameTree(p.left, q.left) && isSameTree(p.right, q.right)
    }
}

---

import Testing

struct Tests {
    private let solution = Solution()
    
    @Test func test1() async throws {
        #expect(solution.isSameTree(TreeNode(1, TreeNode(2), TreeNode(3)),
                                    TreeNode(1, TreeNode(2), TreeNode(3))) == true)
    }
    
    @Test func test2() async throws {
        #expect(solution.isSameTree(TreeNode(1, TreeNode(2), nil),
                                    TreeNode(1, nil, TreeNode(2))) == false)
    }
    
    @Test func test3() async throws {
        #expect(solution.isSameTree(TreeNode(1, TreeNode(2), TreeNode(1)),
                                    TreeNode(1, TreeNode(1), TreeNode(2))) == false)
    }
}