LeetCode-Shuffle an Array

LiBlog發表於2016-08-17
LeetCode

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();

Solution:
 1 public class Solution {
 2     int[] numArr;
 3 
 4     public Solution(int[] nums) {
 5         numArr = new int[nums.length];
 6         for (int i=0;i<nums.length;i++){
 7             numArr[i] = nums[i];
 8         }
 9     }
10     
11     /** Resets the array to its original configuration and return it. */
12     public int[] reset() {
13         return numArr;
14     }
15     
16     /** Returns a random shuffling of the array. */
17     public int[] shuffle() {
18         int[] randArr = new int[numArr.length];
19         for (int i=0;i<numArr.length;i++) randArr[i] = numArr[i];
20         int last = numArr.length-1;
21         Random engine = new Random();
22         while (last>=0){
23             int target = engine.nextInt(last+1);
24             int temp = randArr[last];
25             randArr[last] = randArr[target];
26             randArr[target] = temp;
27             last--;
28         }
29         return randArr;
30     }
31 }
32 
33 /**
34  * Your Solution object will be instantiated and called as such:
35  * Solution obj = new Solution(nums);
36  * int[] param_1 = obj.reset();
37  * int[] param_2 = obj.shuffle();
38  */

 

相關文章