Question

THE STRING MATCH PROBLEM

C++ only. Must use loops. Please do not use sequence of if statements. .

Given 2 strings, a and b, set result to the number of the positions where they contain the same length 2 substring. So "xxcaazz" and "xxbaaz" yields 3, since the "xx", "aa", and "az" substrings appear in the same place in both strings.

• for input of "xxcaazz", "xxbaaz" → 3

• for input of "abc", "abc" → 2

• for input of "abc", "axc" → 0

Answer 1

Here, we want to find the number of positions where they contain the same length 2 substrings. So, for this we follow the following algorithm:

1. Loop through the first string and hold the substring.
   string aSubString = a.substr(i, 2);
2. Now loop through the second string, hold the substring for the second string and check whether the substring which we are holding from the first string matched from the substring of the second string or not.
   string bSubString = b.substr(j, 2);
   if (aSubString == bSubString) { //counter. }
3. If substrings are matching, then increase the counter by 1.
   c++; // Here c is the counter.
4. Return the counter at the end of the program.

Please refer to the comments of the program for more clarity.

#include<bits/stdc++.h>
using namespace std;

int countMatching(string a, string b) {  // Function to find the number of matching sub-strings
    int c = 0; // Initialized the counter by 0

    for (int i = 0; i < a.length() - 1; i++) {  // Loop for string a

        for (int j = 0; j < b.length() - 1; j++) {  // Loop for string b
            string aSubString = a.substr(i, 2);    // Finding substring of a for matching
            string bSubString = b.substr(j, 2);    // Finding the substring of b for matching
            if (aSubString == bSubString) {
                c++;                               // If matching then increase the counter by 1
            }
        }
    }
    return c;  // Returning the answer
}

int main()
{
    /*
        Here we are taking string a and string b as input, you can also replace it with the initialized strings.
    */
    string a,b;
    cin >> a >> b;
    int ans = countMatching(a, b); // Calling the function
    cout << ans << endl;           // Printing the result
    return 0;
}
/*
Sample Input/Output:

Input:
xxcaazz
xxbaaz

Output:
3
*/

I am also attaching sample inputs and outputs for your reference.

Please let me know in the comments if you have any confusion. Also, please upvote if you like.