Gidhub BE Developer

# LeetCode : 384. Shuffle an Array

2021-03-06
goodGid

## Problem

• Need to Retry
``````Given an integer array nums, design an algorithm to randomly shuffle the array.

Implement the Solution class:

Solution(int[] nums) Initializes the object with the integer array nums.
int[] reset() Resets the array to its original configuration and returns it.
int[] shuffle() Returns a random shuffling of the array.
``````

## Example

``````Input
["Solution", "shuffle", "reset", "shuffle"]
[[[1, 2, 3]], [], [], []]
Output
[null, [3, 1, 2], [1, 2, 3], [1, 3, 2]]

Explanation
Solution solution = new Solution([1, 2, 3]);
solution.shuffle();    // Shuffle the array [1,2,3] and return its result. Any permutation of [1,2,3] must be equally likely to be returned. Example: return [3, 1, 2]
solution.reset();      // Resets the array back to its original configuration [1,2,3]. Return [1, 2, 3]
solution.shuffle();    // Returns the random shuffling of array [1,2,3]. Example: return [1, 3, 2]
``````

## [1] Code (21. 03. 06)

``````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() {
int[] copyiedArray = nums.clone();
for (int j=1; j<copyiedArray.length; j++){
int i = random.nextInt(j + 1);
swap(copyiedArray,i,j);
}

return copyiedArray;
}

private void swap(int[] nums, int i, int j) {
if (i == j) {
return;
}
nums[i] ^= nums[j];
nums[j] ^= nums[i];
nums[i] ^= nums[j];
}
}
``````

Check Point

• 단순 구현 문제

Review

• int[] copyiedArray = nums.clone( );

배열에 array.clone( ) 이라는 메소드를 처음알았다.