Today I have done leetcode's January LeetCoding Challenge with cpp.

January LeetCoding Challenge 4

Description

Minimum Rounds to Complete All Tasks

You are given a 0-indexed integer array tasks, where tasks[i] represents the difficulty level of a task. In each round, you can complete either 2 or 3 tasks of the same difficulty level.

Return the minimum rounds required to complete all the tasks, or -1 if it is not possible to complete all the tasks.

Example 1:

Input: tasks = [2,2,3,3,2,4,4,4,4,4]
Output: 4
Explanation: To complete all the tasks, a possible plan is:
- In the first round, you complete 3 tasks of difficulty level 2. 
- In the second round, you complete 2 tasks of difficulty level 3. 
- In the third round, you complete 3 tasks of difficulty level 4. 
- In the fourth round, you complete 2 tasks of difficulty level 4.  
It can be shown that all the tasks cannot be completed in fewer than 4 rounds, so the answer is 4.

Example 2:

Input: tasks = [2,3,3]
Output: -1
Explanation: There is only 1 task of difficulty level 2, but in each round, you can only complete either 2 or 3 tasks of the same difficulty level. Hence, you cannot complete all the tasks, and the answer is -1.

Constraints:

• 1 <= tasks.length <= 105
• 1 <= tasks[i] <= 109

Solution

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
class Solution {
public:
  int minimumRounds(vector<int>& tasks) {
    map<int, int> count;
    for(auto task : tasks) {
      count[task] += 1;
    }
    int answer = 0;
    for(const auto &[_, c] : count) {
      if(c == 1) return -1;
      int result = INT_MAX;
      if(c % 2 == 0) {
        result = c / 2;
      }
      if((c - 4 > 0 && (c - 4) % 3 == 0) || (c - 2 > 0 && (c - 2) % 3 == 0)) {
        result = c / 3 + 1;
      }
      if(c % 3 == 0) {
        result = c / 3;
      }
      answer += result;
    }
    return answer;
  }
};

// Accepted
// 79/79 cases passed (276 ms)
// Your runtime beats 66.53 % of cpp submissions
// Your memory usage beats 23.86 % of cpp submissions (104.7 MB)