1296.Divide_Array_in_Sets_of_K_Consecutive_Numbers(Medium).md

1296. Divide Array in Sets of K Consecutive Numbers (Medium)

Date and Time: Aug 17, 2024, 21:25 (EST)

Link: https://leetcode.com/problems/divide-array-in-sets-of-k-consecutive-numbers/

Question:

Given an array of integers nums and a positive integer k, check whether it is possible to divide this array into sets of k consecutive numbers.

Return true if it is possible. Otherwise, return false.

Example 1:

Input: nums = [1,2,3,3,4,4,5,6], k = 4

Output: true

Explanation: Array can be divided into [1,2,3,4] and [3,4,5,6].

Example 2:

Input: nums = [3,2,1,2,3,4,3,4,5,9,10,11], k = 3

Output: true

Explanation: Array can be divided into [1,2,3] , [2,3,4] , [3,4,5] and [9,10,11].

Example 3:

Input: nums = [1,2,3,4], k = 3

Output: false

Explanation: Each array should be divided in subarrays of size 3.

Constraints:

• 1 <= k <= nums.length <= 10^5

• 1 <= nums[i] <= 10^9

Walk-through:

This question is the same as the previous question 846. Hand of Straights.

Java Solution:

class Solution {
    public boolean isPossibleDivide(int[] nums, int k) {
        if (nums.length % k != 0) {
            return false;
        }
        Map<Integer, Integer> count = new HashMap<>();
        for (int i: nums) {
            count.put(i, count.getOrDefault(i, 0) + 1);
        }
        PriorityQueue<Integer> minHeap = new PriorityQueue<>(count.keySet());
        while (!minHeap.isEmpty()) {
            int first = minHeap.peek();
            for (int i = first; i < first + k; i++) {
                if (!count.containsKey(i)) {
                    return false;
                }
                count.put(i, count.get(i) - 1);
                if (count.get(i) == 0) {
                    if (i != minHeap.peek()) {
                        return false;
                    }
                    minHeap.poll();
                }
            }
        }
        return true;
    }
}

Time Complexity: $O(nlog\ n)$
Space Complexity: $O(n)$