Program to generate a random number between L to R
Write a program that generates a random number within a specified range [L, R]. The program should take two integers, L and R, as input and output a random number between L and R (inclusive).
Examples:
Input: L = 10, R = 20
Output: 15Input: L = -5, R = 5
Output: 3
Approach: To solve the problem, follow the below idea:
We can generate a random number in the range [L, R] by finding how many numbers are there between L to R by the formula: diff = (R – L + 1). Now, we can generate a random number and modulo the random number by diff and add the remainder to L to get a random number between L to R.
Step-by-step algorithm:
- Find the difference between L to R by (R – L + 1).
- Now, generate a random number and modulo it by the above difference.
- Scale and shift the random number by adding the remainder to L to fit within the specified range [L, R].
Below is the implementation of the algorithm:
C++
#include <cstdlib> #include <ctime> #include <iostream> using namespace std; int main() { int L = 10, R = 20; srand ( time (NULL)); int random_number = L + rand () % (R - L + 1); cout << random_number << endl; return 0; } |
C
#include <stdio.h> #include <stdlib.h> #include <time.h> int main() { int L = 10, R = 20; srand ( time (NULL)); int random_number = L + rand () % (R - L + 1); printf ( "%d\n" , random_number); return 0; } |
Java
import java.util.Scanner; public class RandomNumberGenerator { public static void main(String[] args) { int L = 10 ; int R = 20 ; int random_number = L + ( int ) (Math.random() * (R - L + 1 )); System.out.println(random_number); } } |
Python3
import random L, R = 10 , 20 random_number = random.randint(L, R) print (random_number) |
C#
using System; class Program { static void Main() { int L = 10; int R = 20; Random rand = new Random(); int random_number = rand.Next(L, R + 1); Console.WriteLine(random_number); } } |
Javascript
let L = 10 let R = 20 let random_number = Math.floor(Math.random() * (R - L + 1)) + L; console.log(random_number); |
15
Time Complexity: O(1), as it takes constant time to generate a random number.
Auxiliary Space: O(1)
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