added leetcode evaluate polish notation
added leetcode lru cache
added leetcode maximum depth of binary tree
added leetcode same tree
added leetcode reverse integer
added leetcode plus one
added leetcode sort colors
added leetcode remove element
added leetcode climbing stairs
added leetcode permutations
removed comment
removed set matrix zeroes
removed set palindrome number
added leetcode length of last word
added leetcode subsets
added hr manasa and stones