Minimum changes required to make first string substring of second string
Given two strings S1 and S2 ( size of S1 <= Size of S2 ). The task is to find the minimum number of characters to be replaced in the string S2, such that the string S1 is a substring of S2.
Examples:
Input : S1 = cdef, S2 = abbdef Output : 1 Input : S1 = gfg, S2 = fgg Output : 2
Approach:
- Traverse the string S2
- From every index in S2, check the number of mis-matching characters in substring of length of S1
- Store and update the minimum of prev and current mis-match in ans
- Return ans.
Below is the implementation of the above approach:
C++
// CPP program to find the minimum number of // characters to be replaced in string S2, such // that S1 is a substring of S2 #include <bits/stdc++.h> using namespace std; // Function to find the minimum number of // characters to be replaced in string S2, such // that S1 is a substring of S2 int minimumChar(string S1, string S2) { // Get the sizes of both strings int n = S1.size(), m = S2.size(); int ans = INT_MAX; // Traverse the string S2 for (int i = 0; i < m - n + 1; i++) { int minRemovedChar = 0; // From every index in S2, check the number of // mis-matching characters in substring of // length of S1 for (int j = 0; j < n; j++) { if (S1[j] != S2[i + j]) { minRemovedChar++; } } // Take minimum of prev and current mis-match ans = min(minRemovedChar, ans); } // return answer return ans; } // Driver Code int main() { string S1 = "abc"; string S2 = "paxzk"; cout << minimumChar(S1, S2); return 0; } |
Java
// Java program to find the minimum // number of characters to be // replaced in string S2, such // that S1 is a substring of S2 import java.io.*; class GFG { // Function to find the minimum // number of characters to be // replaced in string S2, such // that S1 is a substring of S2 static int minimumChar(String S1, String S2) { // Get the sizes of both strings int n = S1.length(); int m = S2.length(); int ans = Integer.MAX_VALUE ; // Traverse the string S2 for (int i = 0; i < m - n + 1; i++) { int minRemovedChar = 0; // From every index in S2, check // the number of mis-matching // characters in substring of // length of S1 for (int j = 0; j < n; j++) { if (S1.charAt(j) != S2.charAt(i + j)) { minRemovedChar++; } } // Take minimum of prev and // current mis-match ans = Math.min(minRemovedChar, ans); } // return answer return ans; } // Driver Code public static void main (String[] args) { String S1 = "abc"; String S2 = "paxzk"; System.out.println(minimumChar(S1, S2)); } } // This code is contributed by Shashank |
Python3
# Python3 program to find the minimum # number of characters to be replaced # in string S2, such that S1 is a # substring of S2 import sys # Function to find the minimum number of # characters to be replaced in string S2, # such that S1 is a substring of S2 def minimumChar(S1, S2): # Get the sizes of both strings n, m = len(S1), len(S2) ans = sys.maxsize # Traverse the string S2 for i in range(m - n + 1): minRemovedChar = 0 # From every index in S2, check the # number of mis-matching characters # in substring of length of S1 for j in range(n): if (S1[j] != S2[i + j]): minRemovedChar += 1 # Take minimum of prev and # current mis-match ans = min(minRemovedChar, ans) # return answer return ans # Driver Code if __name__ == '__main__': S1 = "abc" S2 = "paxzk" print(minimumChar(S1, S2)) # This code is contributed # by PrinciRaj1992 |
C#
// C# program to find the minimum // number of characters to be // replaced in string S2, such // that S1 is a substring of S2 using System; class GFG { // Function to find the minimum // number of characters to be // replaced in string S2, such // that S1 is a substring of S2 static int minimumChar(String S1, String S2) { // Get the sizes of both strings int n = S1.Length; int m = S2.Length; int ans = Int32.MaxValue ; // Traverse the string S2 for (int i = 0; i < m - n + 1; i++) { int minRemovedChar = 0; // From every index in S2, check // the number of mis-matching // characters in substring of // length of S1 for (int j = 0; j < n; j++) { if (S1[j] != S2[i + j]) { minRemovedChar++; } } // Take minimum of prev and // current mis-match ans = Math.Min(minRemovedChar, ans); } // return answer return ans; } // Driver Code public static void Main() { String S1 = "abc"; String S2 = "paxzk"; Console.WriteLine(minimumChar(S1, S2)); } } // This code is contributed // by Akanksha Rai(Abby_akku) |
PHP
<?php // PHP program to find the minimum // number of characters to be replaced // in string S2, such that S1 is a // substring of S2 // Function to find the minimum number // of characters to be replaced in // string S2, such that S1 is a // substring of S2 function minimumChar($S1, $S2) { // Get the sizes of both strings $n = strlen($S1); $m = strlen($S2); $ans = PHP_INT_MAX; // Traverse the string S2 for ($i = 0; $i < $m - $n + 1; $i++) { $minRemovedChar = 0; // From every index in S2, check // the number of mis-matching // characters in substring of // length of S1 for ($j = 0; $j < $n; $j++) { if ($S1[$j] != $S2[$i + $j]) { $minRemovedChar++; } } // Take minimum of prev and // current mis-match $ans = min($minRemovedChar, $ans); } // return answer return $ans; } // Driver Code $S1 = "abc"; $S2 = "paxzk"; echo minimumChar($S1, $S2); // This code is contributed by ajit. ?> |
Output:
2
Time Complexity: O(N * M).
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