Reverse the given string in the range [L, R] Last Updated : 19 Oct, 2022 Comments Improve Suggest changes Like Article Like Report Given a string str, and two integers L and R, the task is to reverse the string in the range [L, R] i.e. str[L...R].Examples: Input: str = "geeksforgeeks", L = 5, R = 7 Output: geeksrofgeeks Reverse the characters in the range str[5...7] = "geeksforgeeks" and the new string will be "geeksrofgeeks" Input: str = "ijklmn", L = 1, R = 2 Output: ikjlmn Approach: If the range is invalid i.e. either L < 0 or R ? len or L > R then print the original string.If the range is valid then keep swapping the characters str[L] and str[R] while L < R and update L = L + 1 and R = R - 1 after every swap operation. Print the updated string in the end. Below is the implementation of the above approach: C++ // C++ implementation of the approach #include <bits/stdc++.h> using namespace std; // Function to return the string after // reversing characters in the range [L, R] string reverse(string str, int len, int l, int r) { // Invalid range if (l < 0 || r >= len || l > r) return str; // While there are characters to swap while (l < r) { // Swap(str[l], str[r]) char c = str[l]; str[l] = str[r]; str[r] = c; l++; r--; } return str; } // Driver code int main() { string str = "geeksforgeeks"; int len = str.length(); int l = 5, r = 7; cout << reverse(str, len, l, r); return 0; } Java // Java implementation of the approach import java.util.*; class GFG { // Function to return the string after // reversing characters in the range [L, R] static String reverse(char[] str, int len, int l, int r) { // Invalid range if (l < 0 || r >= len || l > r) return "Invalid range!"; // While there are characters to swap while (l < r) { // Swap(str[l], str[r]) char c = str[l]; str[l] = str[r]; str[r] = c; l++; r--; } String string = new String(str); return string; } // Driver code public static void main (String[] args) { String str = "geeksforgeeks"; int len = str.length(); int l = 5, r = 7; System.out.println(reverse(str.toCharArray(), len, l, r)); } } // This code is contributed by Ashutosh450 Python3 # Python3 implementation of the approach # Function to return the string after # reversing characters in the range [L, R] def reverse(string, length, l, r) : # Invalid range if (l < 0 or r >= length or l > r) : return string; string = list(string) # While there are characters to swap while (l < r) : # Swap(str[l], str[r]) c = string[l]; string[l] = string[r]; string[r] = c; l += 1; r -= 1; return "".join(string); # Driver code if __name__ == "__main__" : string = "geeksforgeeks"; length = len(string); l = 5; r = 7; print(reverse(string, length, l, r)); # This code is contributed by AnkitRai01 C# // C# implementation of the approach using System; class GFG { // Function to return the string after // reversing characters in the range [L, R] static String reverse(char[] str, int len, int l, int r) { // Invalid range if (l < 0 || r >= len || l > r) return "Invalid range!"; // While there are characters to swap while (l < r) { // Swap(str[l], str[r]) char c = str[l]; str[l] = str[r]; str[r] = c; l++; r--; } return String.Join("",str); } // Driver code public static void Main (String[] args) { String str = "geeksforgeeks"; int len = str.Length; int l = 5, r = 7; Console.WriteLine(reverse(str.ToCharArray(), len, l, r)); } } // This code is contributed by 29AjayKumar JavaScript <script> // Javascript implementation of the approach // Function to return the string after // reversing characters in the range [L, R] function reverse(str, len, l, r) { // Invalid range if (l < 0 || r >= len || l > r) return "Invalid range!"; // While there are characters to swap while (l < r) { // Swap(str[l], str[r]) let c = str[l]; str[l] = str[r]; str[r] = c; l++; r--; } return str.join(""); } let str = "geeksforgeeks"; let len = str.length; let l = 5, r = 7; document.write(reverse(str.split(''), len, l, r)); // This code is contributed by divyeshrabadiya07. </script> Output: geeksrofgeeks Time complexity: O(N), where N = (r - l)/2Auxiliary space: O(1) Comment More infoAdvertise with us Next Article Reverse the given string in the range [L, R] koulick_sadhu Follow Improve Article Tags : Strings DSA Reverse substring Practice Tags : ReverseStrings Similar Reads Reverse given range of String for M queries Given a string S of length N and an array of queries A[] of size M, the task is to find the final string after performing M operations on the string. 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