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Implemented/Added #LeetCode324 (Wiggle Sort) to JAVA. #36

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Oct 30, 2024
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Implemented/Added #LeetCode324 (Wiggle Sort) to JAVA. #36

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39 changes: 39 additions & 0 deletions Java/WiggleSort.java
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import java.util.Arrays;
import java.util.Scanner;

public class WiggleSort {
public static void wiggleSort(int[] nums) {
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issue (complexity): Consider using a single-pass in-place swapping approach instead of sorting and cloning the array.

The current implementation unnecessarily sorts the entire array and uses O(n) extra space. The wiggle property can be achieved more efficiently with a single pass and O(1) space complexity. Here's a simpler approach:

public static void wiggleSort(int[] nums) {
    for (int i = 0; i < nums.length - 1; i++) {
        if ((i % 2 == 0) == (nums[i] > nums[i + 1])) {
            // Swap if current relationship doesn't match desired pattern
            int temp = nums[i];
            nums[i] = nums[i + 1];
            nums[i + 1] = temp;
        }
    }
}

This solution:

  • Eliminates extra array allocation
  • Removes the need for sorting
  • Uses a single pass through the array
  • Maintains the wiggle property by ensuring even indices are local minimums and odd indices are local maximums

int n = nums.length;
int[] sorted = nums.clone();
Arrays.sort(sorted);

int j = n - 1;
for (int i = 1; i < n; i += 2) {
nums[i] = sorted[j--];
}

for (int i = 0; i < n; i += 2) {
nums[i] = sorted[j--];
}
}

public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
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issue (bug_risk): Scanner resource should be closed after use

Consider using try-with-resources to ensure proper closure of the Scanner object.


System.out.print("Enter the number of elements: ");
int n = scanner.nextInt();

int[] nums = new int[n];
System.out.println("Enter the elements:");
for (int i = 0; i < n; i++) {
nums[i] = scanner.nextInt();
}

wiggleSort(nums);

System.out.println("Wiggled array:");
for (int num : nums) {
System.out.print(num + " ");
}
}
}
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