324. Wiggle Sort Ii¶

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324. Wiggle Sort II

Medium

Given an integer array nums, reorder it such that nums[0] < nums[1] > nums[2] < nums[3]....

You may assume the input array always has a valid answer.

Example 1:

Input: nums = [1,5,1,1,6,4]
Output: [1,6,1,5,1,4]
Explanation: [1,4,1,5,1,6] is also accepted.

Example 2:

Input: nums = [1,3,2,2,3,1]
Output: [2,3,1,3,1,2]

Constraints:

• 1 <= nums.length <= 5 * 104
• 0 <= nums[i] <= 5000
• It is guaranteed that there will be an answer for the given input nums.

Follow Up: Can you do it in O(n) time and/or in-place with O(1) extra space?

Solution¶

class Solution {
    static class custom_sort implements Comparator<Integer> {
        @Override
        public int compare(Integer first, Integer second) {
            return Integer.compare(second, first);
        }
    }
    public void wiggleSort(int[] nums) {
        int n = nums.length;
        PriorityQueue<Integer> pq = new PriorityQueue<>(new custom_sort());
        for (int ele : nums) pq.offer(ele);
        int ind = 1;
        while (ind < n) {
            nums[ind] = pq.poll();
            ind += 2;
        }
        ind = 0;
        while (pq.size() > 0) {
            nums[ind] = pq.poll();
            ind += 2;
        }
    }
}

Complexity Analysis¶

• Time Complexity: O(?)
• Space Complexity: O(?)

Approach¶

Detailed explanation of the approach will be added here