384. Shuffle an Array
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.