384. 打乱数组
打乱一个没有重复元素的数组。
示例:
// 以数字集合 1, 2 和 3 初始化数组。
int[] nums = {1,2,3};
Solution solution = new Solution(nums);
// 打乱数组 [1,2,3] 并返回结果。任何 [1,2,3]的排列返回的概率应该相同。
solution.shuffle();
// 重设数组到它的初始状态[1,2,3]。
solution.reset();
// 随机返回数组[1,2,3]打乱后的结果。
solution.shuffle();
class Solution {
private int[] nums;
private int[] originalNums;
public Solution(int[] nums) {
this.nums = nums;
this.originalNums = Arrays.copyOf(nums, nums.length);
}
/**
* Resets the array to its original configuration and return it.
*/
public int[] reset() {
return this.originalNums;
}
/**
* Returns a random shuffling of the array.
*/
public int[] shuffle() {
Random random = new Random();
for (int i = 0; i < nums.length / 2; i++) {
// 每次只需拿第一个元素进行交换即可
swap(nums, 0, random.nextInt(nums.length));
}
return nums;
}
private void swap(int[] nums, int i, int j) {
int temp = nums[i];
nums[i] = nums[j];
nums[j] = temp;
}
}
/**
* Your Solution object will be instantiated and called as such:
* Solution obj = new Solution(nums);
* int[] param_1 = obj.reset();
* int[] param_2 = obj.shuffle();
*/
