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();

给一个没有重复数字的数组，实现重置和洗牌的功能。

解法：遍历数组每个位置，每次都随机生成一个坐标位置，然后交换当前位置和随机位置的数字，这样如果数组有n个数字，那么也随机交换了n组位置，从而达到了洗牌的目的。

Java:

import java.util.Random;public class Solution {    private int[] nums;    private Random random;    public Solution(int[] nums) {        this.nums = nums;        random = new Random();    }        /** Resets the array to its original configuration and return it. */    public int[] reset() {        return nums;    }        /** Returns a random shuffling of the array. */    public int[] shuffle() {        if(nums == null) return null;        int[] a = nums.clone();        for(int j = 1; j < a.length; j++) {            int i = random.nextInt(j + 1);            swap(a, i, j);        }        return a;    }        private void swap(int[] a, int i, int j) {        int t = a[i];        a[i] = a[j];        a[j] = t;    }}　　

Python:

import randomclass Solution(object):    def __init__(self, nums):        """        :type nums: List[int]        :type size: int        """        self.__nums = nums    def reset(self):        """        Resets the array to its original configuration and return it.        :rtype: List[int]        """        return self.__nums    def shuffle(self):        """        Returns a random shuffling of the array.        :rtype: List[int]        """        nums = list(self.__nums)        for i in xrange(len(nums)):            j = random.randint(i, len(nums)-1)            nums[i], nums[j] = nums[j], nums[i]        return nums# Your Solution object will be instantiated and called as such:# obj = Solution(nums)# param_1 = obj.reset()# param_2 = obj.shuffle()　　

C++:

class Solution {public:    Solution(vector
     
       nums): v(nums) {}        /** Resets the array to its original configuration and return it. */    vector
      
        reset() {        return v;    }        /** Returns a random shuffling of the array. */    vector
       
         shuffle() {        vector
        
          res = v;        for (int i = 0; i < res.size(); ++i) {            int t = i + rand() % (res.size() - i);            swap(res[i], res[t]);        }        return res;    }    private:    vector
         
           v;};