Count_Substrings_That_Differ_By_One_Character.cpp

PROBLEM STATEMENT :-
  Given two strings s and t, find the number of ways you can choose a non-empty substring of s and replace a single character by a different character such that the 
  resulting substring is a substring of t. In other words, find the number of substrings in s that differ from some substring in t by exactly one character.
  For example, the underlined substrings in "computer" and "computation" only differ by the 'e'/'a', so this is a valid way.Return the number of substrings 
  that satisfy the condition above.
  A substring is a contiguous sequence of characters within a string.
  
  Example 1:

Input: s = "aba", t = "baba"
Output: 6
Explanation: The following are the pairs of substrings from s and t that differ by exactly 1 character:
("aba", "baba")
("aba", "baba")
("aba", "baba")
("aba", "baba")
("aba", "baba")
("aba", "baba")
The underlined portions are the substrings that are chosen from s and t.
  
 Example 2:
Input: s = "ab", t = "bb"
Output: 3
Explanation: The following are the pairs of substrings from s and t that differ by 1 character:
("ab", "bb")
("ab", "bb")
("ab", "bb")
The underlined portions are the substrings that are chosen from s and t.
  
  
  SOLUTION :-
    
    class Solution 
    {
public:
    int countSubstrings(string s, string t) 
    {
        int ans=0 , m=s.size() , n=t.size();
        for(int i=0;i<m;i++)
        {
            for(int j=0;j<n;j++)
            {
                if(s[i]!=t[j])
                {
                    int left=1,right=1;
                    while(i-left>=0 && j-left>=0 && s[i-left]==t[j-left])
                        left+=1;
                    while(j+right<n && i+right<m && s[i+right] == t[j+right] )
                        right+=1;
                    
                    ans+=(left * right);
                }
                else
                    continue;
            }
        }
        return ans;
    }
};