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();
题意：
洗牌
Solution1：
code
1 class Solution { 2 int[] origin; 3 int[] nums; 4 Random random; 5 6 public Solution(int[] nums) { 7 origin = copy(nums); 8 this.nums = copy(nums); 9 random = new Random(); 10 } 11 12 /** Resets the array to its original configuration and return it. */ 13 public int[] reset() { 14 nums = copy(origin); 15 random = new Random(); 16 return nums; 17 18 } 19 20 /** Returns a random shuffling of the array. */ 21 public int[] shuffle() { 22 final int n = nums.length; 23 int[] result = new int[n]; 24 25 for(int i = n; i>=1; i--){ 26 int randomIdx = random.nextInt(i); 27 result[n - i] = nums[randomIdx]; 28 int temp = nums[randomIdx]; 29 nums[randomIdx] = nums[i - 1]; 30 nums[i - 1] = temp; 31 } 32 return result; 33 } 34 35 private int[] copy(int[] array){ 36 int[] result = new int[array.length]; 37 for(int i = 0; i < array.length; i++){ 38 result[i] = array[i]; 39 } 40 return result; 41 } 42 } 43 44 /** 45 * Your Solution object will be instantiated and called as such: 46 * Solution obj = new Solution(nums); 47 * int[] param_1 = obj.reset(); 48 * int[] param_2 = obj.shuffle(); 49 */
