Problem

Given two strings s and t which consist of only lowercase letters.

String t is generated by random shuffling string s and then add one more letter at a random position.

Find the letter that was added in t.

Example:

Input:

s = “abcd”

t = “abcde”

Output: e

Explanation: ‘e’ is the letter that was added.

Pre analysis

It is same as finding extra number in two arrays. will substract summation of one with other.

Another Solution

1. Same Approach using ^

   var findTheDifference = function(s, t) {
       let result = 0;
       for(let i=0;i<t.length;i++) {
           result = result ^ t.charCodeAt(i);
           if(i<=s.length-1) {
               result = result ^ s.charCodeAt(i);
           }
       }
   
       return String.fromCharCode(result);
   };
   

2. Sorting and finding O(N2)

   var findTheDifference = function(s, t) {
       s = s.split('').sort();
       t = t.split('').sort();
   
       for(let i = 0; i < t.length; i++) {
           if(s[i] !== t[i]) {
               return t[i]
           }
       }
   };