1296.IsPossibleDivide.cs

// 1296. Divide Array in Sets of K Consecutive Numbers
// 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 <= 105
// 1 <= nums[i] <= 109

public class Solution {
    public bool IsPossibleDivide(int[] nums, int k) {
        if(nums.Length%k != 0)
            return false;
        
        Array.Sort(nums);

        Dictionary<int,int> freq = new();
        foreach(var num in nums){
            if(freq.ContainsKey(num))
                freq[num]++;
            else
                freq[num] = 1;
        }
        while(freq.Any()){
            int num = freq.First().Key;
            for(int i = 0; i < k; i++){
                int currNum = num  + i;
                if(freq.ContainsKey(currNum)){
                    freq[currNum]--;
                    if(freq[currNum] == 0)
                        freq.Remove(currNum);
                }
                else
                    return false;
            }
        }
        return true;
    }
}