Find last index of a character in a string
Given a string str and a character x, find last index of x in str.
Count of index pairs (i, j) such that string after deleting ith character is equal to string after deleting jth character
Last remaining character after repeated removal of the first character and flipping of characters of a Binary String
Check if frequency of character in one string is a factor or multiple of frequency of same character in other string
Find a string such that every character is lexicographically greater than its immediate next character