Queries for characters in a repeated string

Read

Discuss

Given a string, X. Form a string S by repeating string X multiple times i.e appending string X multiple times with itself. There are Q queries of forms i and j. The task is to print “Yes” if the element at index i is the same as the element at index j in S else print “No” for each query.

Examples :

Input : X = "geeksforgeeks", Q = 3.
Query 1: 0 8
Query 2: 8 13
Query 3: 6 15

Output :
Yes
Yes
No

String S will be "geeksforgeeksgeeksforgeeks....".
For Query 1, index 0 and index 8 have same element i.e 'g'.
For Query 2, index 8 and index 13 have same element i.e 'g'.
For Query 3, index 6 = 'o' and index 15 = 'e' which are not same.

Let the length of string X be n. Observe that elements at indexes 0, n, 2n, 3n,…. are the same. Similarly for index i, position i, n+i, 2n+i, 3n+i,….. contain same element.
So, for each query, find (i%n) and (j%n), and if both are the same for string X.

Below is the implementation of the above idea:

C++

// Queries for same characters in a repeated
// string
#include <bits/stdc++.h>
using namespace std;
 
// Print whether index i and j have same
// element or not.
void query(char s[], int i, int j)
{
    int n = strlen(s);
 
    // Finding relative position of index i,j.
    i %= n;
    j %= n;
 
    // Checking is element are same at index i, j.
    (s[i] == s[j]) ? (cout << "Yes" << endl)
                   : (cout << "No" << endl);
}
 
// Driven Program
int main()
{
    char X[] = "geeksforgeeks";
 
    query(X, 0, 8);
    query(X, 8, 13);
    query(X, 6, 15);
 
    return 0;
}

Java

// Java Program to Queries for
// same characters in a 
// repeated string
import java.io.*;
 
public class GFG{
     
// Print whether index i and j
// have same element or not
static void query(String s, int i,
                  int j)
{
    int n = s.length();
 
    // Finding relative position
    // of index i,j
    i %= n;
    j %= n;
 
    // Checking is element are same
    // at index i, j
    if(s.charAt(i) == s.charAt(j))
    System.out.println("Yes");
    else
    System.out.println("No");
}
 
    // Driver Code
    static public void main (String[] args)
    {
    String X = "geeksforgeeks";
 
    query(X, 0, 8);
    query(X, 8, 13);
    query(X, 6, 15);
 
    }
}
 
// This code is contributed by vt_m.

Python3

# Queries for same characters in a repeated
# string
 
# Print whether index i and j have same
# element or not.
def query(s, i, j):
    n = len(s)
 
    # Finding relative position of index i,j.
    i %= n
    j %= n
 
    # Checking is element are same at index i, j.
    print("Yes") if s[i] == s[j] else print("No")
 
# Driver code
if __name__ == "__main__":
    X = "geeksforgeeks"
    query(X, 0, 8)
    query(X, 8, 13)
    query(X, 6, 15)
 
# This code is contributed by
# sanjeev2552

C#

// C# Program to Queries for
// same characters in a 
// repeated string
using System;
 
public class GFG{
     
// Print whether index i and j
// have same element or not
static void query(string s, int i, 
                  int j)
{
    int n = s.Length;
 
    // Finding relative position
    // of index i,j.
    i %= n;
    j %= n;
 
    // Checking is element are 
    // same at index i, j
    if(s[i] == s[j])
    Console.WriteLine("Yes");
    else
    Console.WriteLine("No");
}
 
    // Driver Code
    static public void Main ()
    {
    string X = "geeksforgeeks";
 
    query(X, 0, 8);
    query(X, 8, 13);
    query(X, 6, 15);
 
    }
}
 
// This code is contributed by vt_m.

PHP

<?php
// Queries for same characters 
// in a repeated string
 
// Print whether index i and j 
// have same element or not.
function query($s, $i, $j)
{
    $n = strlen($s);
 
    // Finding relative position
    // of index i,j.
    $i %= $n;
    $j %= $n;
 
    // Checking is element are 
    // same at index i, j.
    if(($s[$i] == $s[$j])) 
        echo "Yes\n" ;
    else
        echo "No" ;
}
 
// Driver Code
$X = "geeksforgeeks";
 
query($X, 0, 8);
query($X, 8, 13);
query($X, 6, 15);
 
// This code is contributed by nitin mittal. 
?>

Javascript

<script>
    // Javascript Program to Queries for
    // same characters in a 
    // repeated string
     
    // Print whether index i and j
    // have same element or not
    function query(s, i, j)
    {
        let n = s.length;
 
        // Finding relative position
        // of index i,j.
        i %= n;
        j %= n;
 
        // Checking is element are 
        // same at index i, j
        if(s[i] == s[j])
            document.write("Yes" + "</br>");
        else
            document.write("No" + "</br>");
    }
     
    let X = "geeksforgeeks";
   
    query(X, 0, 8);
    query(X, 8, 13);
    query(X, 6, 15);
     
</script>

Output

Yes
Yes
No

Time complexity: O(1)
Auxiliary Space: O(1)

If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Recommended

Solve DSA problems on GfG Practice.

Solve Problems

Feeling lost in the world of random DSA topics, wasting time without progress? It's time for a change! Join our DSA course, where we'll guide you on an exciting journey to master DSA efficiently and on schedule.
Ready to dive in? Explore our Free Demo Content and join our DSA course, trusted by over 100,000 geeks!

Last Updated : 06 Jul, 2022