Generate a random Binary String of length N

Last Updated : 13 Mar, 2023

Given a positive integer N, the task is to generate a random binary string of length N.

Examples:

Input: N = 7
Output: 1000001

Input: N = 5
Output: 01001

Approach: The given problem can be solved by using the rand() function that generates a random number over the range [0, RAND_MAX] and with the help of the value returned by this function, any number in any range [L, R] can be generated as (rand() % (R - L + 1)) + L. Follow the steps below to solve the problem:

Initialize an empty string, say S.
Iterate over the range [0, N - 1] and perform the following steps:
- Store a random number in the range [0, 1] using rand() function.
- Append the randomly generated 0 or 1 to the end of the string S.
After completing the above steps, print the string S as the resulting binary string.

Below is the implementation of the above approach:

C++

// C++ program for the above approach  #include <bits/stdc++.h> using namespace std;  // Function to find a random // number between 0 or 1 int findRandom() {     // Generate the random number     int num = ((int)rand() % 2);      // Return the generated number     return num; }  // Function to generate a random // binary string of length N void generateBinaryString(int N) {     srand(time(NULL));      // Stores the empty string     string S = "";      // Iterate over the range [0, N - 1]     for (int i = 0; i < N; i++) {          // Store the random number         int x = findRandom();          // Append it to the string         S += to_string(x);     }      // Print the resulting string     cout << S; }  // Driver Code int main() {     int N = 7;     generateBinaryString(N);      return 0; }

Java

// Java program for the above approach class GFG{      // Function to find a random // number between 0 or 1 static int findRandom() {          // Generate the random number     int num = (1 + (int)(Math.random() * 100)) % 2;      // Return the generated number     return num; }  // Function to generate a random // binary string of length N static void generateBinaryString(int N) {          // Stores the empty string     String S = "";      // Iterate over the range [0, N - 1]     for(int i = 0; i < N; i++)     {                  // Store the random number         int x = findRandom();          // Append it to the string         S = S + String.valueOf(x);     }      // Print the resulting string     System.out.println(S); }  // Driver Code public static void main (String[] args) {     int N = 7;          generateBinaryString(N); } }  // This code is contributed by AnkThon

Python3

# Python3 program for the above approach import random  # Function to find a random # number between 0 or 1 def findRandom():          # Generate the random number     num = random.randint(0, 1)      # Return the generated number     return num  # Function to generate a random # binary string of length N def generateBinaryString(N):          # Stores the empty string     S = ""      # Iterate over the range [0, N - 1]     for i in range(N):                  # Store the random number         x = findRandom()          # Append it to the string         S += str(x)          # Print the resulting string     print(S)  # Driver Code N = 7  generateBinaryString(N)  # This code is contributed by sanjoy_62

// C# program for the above approach using System; using System.Collections.Generic; using System.Linq;  public class GFG {      // Function to find a random // number between 0 or 1 static int findRandom() {        // For random generator     Random rand = new Random();          // Generate the random number     int num =  rand.Next() % 2;       // Return the generated number     return num; }   // Function to generate a random // binary string of length N static void generateBinaryString(int N) {           // Stores the empty string     string S = "";       // Iterate over the range [0, N - 1]     for(int i = 0; i < N; i++)     {                   // Store the random number         int x = findRandom();           // Append it to the string         S = S + x.ToString();     }       // Print the resulting string     Console.WriteLine(S); }   // Driver Code public static void Main (string[] args) {          int N = 7;     generateBinaryString(N); } }  // This code is contributed by code_hunt.

JavaScript

   <script>             // Javascript program for the above approach          // Function to find a random         // number between 0 or 1         function findRandom() {             // Generate the random number             let num =              (1 + parseInt((Math.random() * 100))) % 2;              // Return the generated number             return num;         }          // Function to generate a random         // binary string of length N         function generateBinaryString(N) {              // Stores the empty string             let S = "";              // Iterate over the range [0, N - 1]             for (let i = 0; i < N; i++) {                  // Store the random number                 let x = findRandom();                  // Append it to the string                 S += (x).toString();             }              // Print the resulting string             document.write(S)         }          // Driver Code         let N = 7;         generateBinaryString(N);          // This code is contributed by Hritik              </script>

Output:

Time Complexity: O(N) In the above-given approach, there is one loop for iterating over string which takes O(N) time in worst case. Therefore, the time complexity for this approach will be O(N).
Auxiliary Space: O(N)// an extra variable store all the characters of the string and in worst case all characters will be unique hence algorithm takes up linear space

Generate a random permutation of 1 to N

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Generate a random Binary String of length N

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