Shuffle a set of numbers without duplicates.
Example: // Init an array with set 1, 2, and 3.
int[] nums = {1,2,3};
Solution solution = new Solution(nums);
// Shuffle the array [1,2,3] and return its result. Any permutation of [1,2,3] must equally likely to be returned.
solution.shuffle();
// Resets the array back to its original configuration [1,2,3].
solution.reset();
// Returns the random shuffling of array [1,2,3].
solution.shuffle();

数组洗牌， 然后在复归， 这两个功能， 洗牌： 扫描数组， 当前值与他后面任何一个随机数互换。