Given a string str and an integer X. The task is to find whether the first X characters of both string str and reversed string str are same or not. If it is equal then print true, otherwise print false.
Examples:
Input: str = abcdefba, X = 2
Output: true
Explanation:
First 2 characters of both string str and reversed string str are same.Input: str = neveropen, X = 3
Output: false
Approach: This problem can be solved by iterating over the characters of the string str. Follow the steps below to solve this problem:
- Initialize two variables say, i as 0 and n as length of str to store position of current character and length of the string str respectively.
- Iterate while i less than n and x:
- If ith character from starting and ith from the last are not equal, then print false and return.
- After completing the above steps, print true as the answer.
Below is the implementation of the above approach :
C++
// C++ implementation for the above approach#include <bits/stdc++.h>using namespace std;// Function to check whether the first// x characters of both string str and// reversed string str are same or notvoid isEqualSubstring(string str, int x){ // Length of the string str int n = str.length(); int i = 0; // Traverse over the string while // first and last x characters are // not equal while (i < n && i < x) { // If the current and n-k-1 from last // character are not equal if (str[i] != str[n - i - 1]) { cout << "false"; return; } i++; } // Finally, print true cout << "true";}// Driver Codeint main(){ // Given Input string str = "neveropen"; int x = 3; // Function Call isEqualSubstring(str, x);} |
Java
// Java program for the above approachimport java.io.*;class GFG { // Function to check whether the first // x characters of both string str and // reversed string str are same or not public static void isEqualSubstring(String str, int x) { // Length of the string str int n = str.length(); int i = 0; // Traverse over the string while // first and last x characters are // not equal while (i < n && i < x) { // If the current and n-k-1 from last // character are not equal if (str.charAt(i) != str.charAt(n - i - 1)) { System.out.println("false"); return; } i++; } // Finally, print true System.out.println("true"); } // Driver Code public static void main(String[] args) { // Given Input String str = "neveropen"; int x = 3; // Function Call isEqualSubstring(str, x); }} |
Python3
# Python3 program for the above approach# Function to check whether the first# x characters of both string str and# reversed string str are same or notdef isEqualSubstring(string, x): # Length of the string str n = len(string) i = 0 # Traverse over the string while # first and last x characters are # not equal while i < n and i < x: # If the current and n-k-1 from last # character are not equal if (string[i] != string[n-i-1]): print("false") return i += 1 # Finally, print true print("true") return# Driver Codeif __name__ == '__main__': # Given input string = "neveropen" x = 3 # Function Call isEqualSubstring(string, x)# This code is contributed by MuskanKalra1 |
C#
// C# implementation for the above approachusing System;using System.Collections.Generic;class GFG{// Function to check whether the first// x characters of both string str and// reversed string str are same or notstatic void isEqualSubstring(string str, int x){ // Length of the string str int n = str.Length; int i = 0; // Traverse over the string while // first and last x characters are // not equal while (i < n && i < x) { // If the current and n-k-1 from last // character are not equal if (str[i] != str[n - i - 1]) { Console.Write("false"); return; } i++; } // Finally, print true Console.Write("true");}// Driver Codepublic static void Main(){ // Given Input string str = "neveropen"; int x = 3; // Function Call isEqualSubstring(str, x);}}// This code is contributed by ipg2016107. |
Javascript
<script> // JavaScript program for the above approach // Function to check whether the first// x characters of both string str and// reversed string str are same or notfunction isEqualSubstring(str, x){ // Length of the string str let n = str.length; let i = 0; // Traverse over the string while // first and last x characters are // not equal while (i < n && i < x) { // If the current and n-k-1 from last // character are not equal if (str[i] !== str[n - i - 1]) { document.write("false"); return; } i++; } // Finally, print true document.write("true");}// Driver Code // Given Input let str = "neveropen"; let x = 3; // Function Call isEqualSubstring(str, x); // This code is contributed by Potta Lokesh </script> |
Output
false
Time complexity: O(min(n, k))
Auxiliary Space: O(1)
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