**Templates - ALawliet/algorithms GitHub Wiki https://leetcode.com/problems/find-k-th-smallest-pair-distance/discuss/769705/Python-Clear-explanation-Powerful-Ultimate-Binary-Search-Template.-Solved-many-problems. https://www.youtube.com/watch?v=s2Yyk3qdy3o&t=152s&ab_channel=Insidecode https://leetcode.com/problems/palindrome-permutation-ii/discuss/69717/Backtrack-Summary%3A-General-Solution-for-10-Questions!!!!!!!!-Python-(Combination-Sum-Subsets-Permutation-Palindrome)