Maximize Sum Of Array After K Negations

LeetCode Q 1005 - Maximize Sum Of Array After K Negations

Given an array A of integers, we must modify the array in the following way: we choose an i and replace A[i] with -A[i], and we repeat this process K times in total. (We may choose the same index i multiple times.)

Return the largest possible sum of the array after modifying it in this way.

Example 1: Input: A = [4,2,3], K = 1 ; Output: 5
Explanation: Choose indices (1,) and A becomes [4,-2,3].

Example 2: Input: A = [3,-1,0,2], K = 3 ; Output: 6
Explanation: Choose indices (1, 2, 2) and A becomes [3,1,0,2].

Example 3: Input: A = [2,-3,-1,5,-4], K = 2 ; Output: 13
Explanation: Choose indices (1, 4) and A becomes [2,3,-1,5,4].

Note:

• 1 <= A.length <= 10000
• 1 <= K <= 10000
• -100 <= A[i] <= 100

Solution

Code:

public int largestSumAfterKNegations(int[] A, int K) {

	PriorityQueue<Integer> pq = new PriorityQueue<>();

	for (int num: A) pq.offer(num);

	while (K != 0) {
		pq.offer(pq.poll() * -1); K--;
	}

	int res = 0;

	while (!pq.isEmpty()) res += pq.poll();

	return res;
}