Given an integer N, the task is to generate N non repeating random numbers.
Input: N = 5
Output: 1 5 2 4 3
Input: N = 8
Output: 7 2 1 8 3 6 4 5
Approach: Create an array of N elements and initialize the elements as 1, 2, 3, 4, …, N then shuffle the array elements using Fisher–Yates shuffle Algorithm.
Fisher–Yates shuffle Algorithm works in O(n) time complexity. The assumption here is, we are given a function rand() that generates random number in O(1) time.
The idea is to start from the last element, swap it with a randomly selected element from the whole array (including last). Now consider the array from 0 to n-2 (size reduced by 1), and repeat the process till we hit the first element.
Below is the implementation of the above approach:
3 4 5 8 6 2 1 7
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