Here is my answer in Java. The function nextInt(bound) always selects a random integer between 0 (inclusive) and the "bound" (exclusive). Thus, you can use the length of the array as the bound so a randomly selected index will always in bounds. My method steps through the array and for each step, a random number (in bounds) is generated and the current index is swapped with the generated one. Therefore, every number in the array has a chance to be shuffled. It runs in linear time: Overall O(n) given n elements. public static void shuffle(int[] array) { Random rand = new Random(); int temp, index; for(int i = 0; i < array.length; i++) { temp = array[i]; index = rand.nextInt(array.length); array[i] = array[index]; array[index] = temp; } }