Task Scheduler

max_freq = max frequency
count_max = number of tasks with max_freq
answer = max(total_tasks, (max_freq - 1) * (n + 1) + count_max)

// C — formula
int leastInterval(char* tasks, int n, int tasksSize) {
    int freq[26] = {0};
    for (int i = 0; i < tasksSize; i++) freq[tasks[i]-'A']++;
    int maxF = 0, countMax = 0;
    for (int i = 0; i < 26; i++) if (freq[i] > maxF) maxF = freq[i];
    for (int i = 0; i < 26; i++) if (freq[i] == maxF) countMax++;
    int ans = (maxF - 1) * (n + 1) + countMax;
    return ans > tasksSize ? ans : tasksSize;
}

// C++
int leastInterval(vector<char>& tasks, int n) {
    vector<int> freq(26, 0);
    for (char t : tasks) freq[t-'A']++;
    int maxF = *max_element(freq.begin(), freq.end());
    int countMax = count(freq.begin(), freq.end(), maxF);
    return max((int)tasks.size(), (maxF - 1) * (n + 1) + countMax);
}

// Java
public int leastInterval(char[] tasks, int n) {
    int[] freq = new int[26];
    for (char t : tasks) freq[t-'A']++;
    int maxF = 0;
    for (int f : freq) maxF = Math.max(maxF, f);
    int countMax = 0;
    for (int f : freq) if (f == maxF) countMax++;
    return Math.max(tasks.length, (maxF - 1) * (n + 1) + countMax);
}

// JavaScript
function leastInterval(tasks, n) {
    const freq = new Array(26).fill(0);
    for (const t of tasks) freq[t.charCodeAt(0) - 65]++;
    const maxF = Math.max(...freq);
    const countMax = freq.filter(f => f === maxF).length;
    return Math.max(tasks.length, (maxF - 1) * (n + 1) + countMax);
}

# Python — formula
from collections import Counter

def leastInterval(tasks, n):
    freq = Counter(tasks)
    max_f = max(freq.values())
    count_max = sum(1 for f in freq.values() if f == max_f)
    return max(len(tasks), (max_f - 1) * (n + 1) + count_max)