Added Program to Check Isomorphic Strings.

[mahatorakesh]

Two strings are isomorphic if the characters in s can be replaced to get t. All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map to the same character but a character may map to itself.

Problem

1. You are given two strings s1 and s2.
2. You have to determine if they are isomorphic or not.
3. Two strings are called isomorphic if -
   -> Every character of s1 can be mapped with characters of s2.
   -> A character of s1 can be mapped to only one character.
   -> All occurrences of a character must be replaced with another character while preserving the order of characters.

Solution

1. If lengths of str1 and str2 are not same, return false.
2. Do following for every character in str1 and str2
   a) If this character is seen first time in str1,
   then current of str2 must have not appeared before.
   (i) If current character of str2 is seen, return false.
   Mark current character of str2 as visited.
   (ii) Store mapping of current characters.
   b) Else check if previous occurrence of str1[i] mapped
   to same character.

Changes proposed in this Pull Request

• Program to Check Isomorphic String.