README_EN.md

2244. Minimum Rounds to Complete All Tasks

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Description

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

Solutions

Python3

class Solution:
    def minimumRounds(self, tasks: List[int]) -> int:
        cnt = Counter(tasks)
        mi = min(cnt.values())
        if mi == 1:
            return -1
        return sum(v // 3 + (0 if v % 3 == 0 else 1) for v in cnt.values())

Java

class Solution {
    public int minimumRounds(int[] tasks) {
        Map<Integer, Integer> cnt = new HashMap<>();
        for (int t : tasks) {
            cnt.put(t, cnt.getOrDefault(t, 0) + 1);
        }
        int ans = 0;
        for (int v : cnt.values()) {
            if (v == 1) {
                return -1;
            }
            ans += v / 3 + (v % 3 == 0 ? 0 : 1);
        }
        return ans;
    }
}

TypeScript

function minimumRounds(tasks: number[]): number {
    let hashMap = new Map();
    for (let key of tasks) {
        hashMap.set(key, (hashMap.get(key) || 0) + 1);
    }
    let ans = 0;
    for (let key of hashMap.keys()) {
        let val = hashMap.get(key);
        if (val < 2) return -1;
        const ctn = Math.floor(val / 3) + (val % 3 == 0 ? 0 : 1);
        ans += ctn;
    }
    return ans;
}

C++

class Solution {
public:
    int minimumRounds(vector<int>& tasks) {
        unordered_map<int, int> cnt;
        for (int& t : tasks) ++cnt[t];
        int ans = 0;
        for (auto& [_, v] : cnt) {
            if (v == 1) return -1;
            ans += v / 3 + (v % 3 == 0 ? 0 : 1);
        }
        return ans;
    }
};

Go

func minimumRounds(tasks []int) int {
	cnt := map[int]int{}
	for _, t := range tasks {
		cnt[t]++
	}
	ans := 0
	for _, v := range cnt {
		if v == 1 {
			return -1
		}
		ans += v / 3
		if v%3 != 0 {
			ans++
		}
	}
	return ans
}

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