Here, We see Task Scheduler LeetCode Solution. This Leetcode problem is done in many programming languages like C++, Java, JavaScript, Python, etc. with different approaches.

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Task Scheduler LeetCode Solution

Problem Statement

You are given an array of CPU tasks, each represented by letters A to Z, and a cooling time, n. Each cycle or interval allows the completion of one task. Tasks can be completed in any order, but there’s a constraint: identical tasks must be separated by at least n intervals due to cooling time.

​Return the minimum number of intervals required to complete all tasks.

Example 1:
Input: tasks = [“A”,”A”,”A”,”B”,”B”,”B”], n = 2
Output: 8
Explanation: A possible sequence is: A -> B -> idle -> A -> B -> idle -> A -> B.
After completing task A, you must wait two cycles before doing A again. The same applies to task B. In the 3^rd interval, neither A nor B can be done, so you idle. By the 4^th cycle, you can do A again as 2 intervals have passed.

Example 2:
Input: tasks = [“A”,”C”,”A”,”B”,”D”,”B”], n = 1
Output: 6
Explanation: A possible sequence is: A -> B -> C -> D -> A -> B.
With a cooling interval of 1, you can repeat a task after just one other task.

Example 3:
Input: tasks = [“A”,”A”,”A”, “B”,”B”,”B”], n = 3
Output: 10
Explanation: A possible sequence is: A -> B -> idle -> idle -> A -> B -> idle -> idle -> A -> B.
There are only two types of tasks, A and B, which need to be separated by 3 intervals. This leads to idling twice between repetitions of these tasks.

Task Scheduler LeetCode Solution C++

class Solution {
public:
    int leastInterval(vector<char>& tasks, int n) {
        int freq[26] = {0};
        for(char task : tasks){
            freq[task - 'A']++;
        }
        sort(begin(freq) , end(freq));
        int chunk = freq[25] - 1;
        int idel = chunk * n;
        for(int i=24; i>=0; i--){
            idel -= min(chunk,freq[i]);
        }
        return idel < 0 ? tasks.size() : tasks.size() + idel;
    }
};Code language: PHP (php)

Task Scheduler LeetCode Solution Java

class Solution {
    public int leastInterval(char[] tasks, int n) {
        int[] freq = new int[26];
        for (char task : tasks) {
            freq[task - 'A']++;
        }
        Arrays.sort(freq);
        int chunk = freq[25] - 1;
        int idle = chunk * n;
        for (int i = 24; i >= 0; i--) {
            idle -= Math.min(chunk, freq[i]);
        }
        return idle < 0 ? tasks.length : tasks.length + idle;
    }
}Code language: JavaScript (javascript)

Task Scheduler Solution JavaScript

var leastInterval = function(tasks, n) {
    let freq = Array(26).fill(0);
    for (let task of tasks) {
        freq[task.charCodeAt(0) - 'A'.charCodeAt(0)]++;
    }
    freq.sort((a, b) => b - a);
    let chunk = freq[0] - 1;
    let idle = chunk * n;
    for (let i = 1; i < 26; i++) {
        idle -= Math.min(chunk, freq[i]);
    }
    return idle < 0 ? tasks.length : tasks.length + idle;
};Code language: JavaScript (javascript)

Task Scheduler Solution Python

class Solution(object):
    def leastInterval(self, tasks, n):
        freq = [0] * 26
        for task in tasks:
            freq[ord(task) - ord('A')] += 1
        freq.sort()
        chunk = freq[25] - 1
        idle = chunk * n

        for i in range(24, -1, -1):
            idle -= min(chunk, freq[i])

        return len(tasks) + idle if idle >= 0 else len(tasks)