# LeetCode Çözümleri – 101. Symmetric Tree

LeetCode içerisinde bulunan “Symmetric Tree” sorusunun açıklaması ve çözümü. Size root’u verilen bir binary tree‘nin merkezine göre simetrik olup olmadığını bulmanız isteniyor.

► LeetCode 101. Symmetric Tree: https://leetcode.com/problems/symmetric-tree/

► Problem açıklaması:

Given the root of a binary tree, check whether it is a mirror of itself (i.e., symmetric around its center).

Input: root = [1,2,2,3,4,4,3]

Output: true

Input: root = [1,2,2,null,3,null,3]

Output: false

Constraints:

The number of nodes in the tree is in the range [1, 1000].

-100 <= Node.val <= 100

Follow up: Could you solve it both recursively and iteratively?

# HackerRank Çözümleri – Alternating Characters

HackerRank içerisinde bulunan “Alternating Characters” sorusunun açıklaması ve çözümü. Soruda size verilen string içerisinde, yan yana hiçbir karakterin aynı olmaması için kaç defa karakter silme işlemi yapmanız gerektiği soruluyor.

► HackerRank – Alternating Characters: https://www.hackerrank.com/challenges/alternating-characters/problem

► Problem açıklaması:

You are given a string containing characters A and B only. Your task is to change it into a string such that there are no matching adjacent characters. To do this, you are allowed to delete zero or more characters in the string.

Example

s = AABAAB

Remove an A at positions 0 and 3 to make s = ABAB in 2 deletions.

Function Description

Complete the alternatingCharacters function in the editor below.

alternatingCharacters has the following parameter(s):

string s: a string

Returns

int: the minimum number of deletions required

Sample Input

5

AAAA

BBBBB

ABABABAB

BABABA

AAABBB

Sample Output

3

4

0

0

4