Task Scheduler: coding question

Problem

You get an array tasks and an integer n. Each task is an uppercase letter, and equal letters are tasks of the same kind.

A CPU is the processor of a computer. The CPU completes the tasks in time intervals. In each interval, the CPU completes one task or stays idle. Two tasks of the same kind must have at least n intervals between them.

You can complete the tasks in any order. Return the minimum number of intervals that the CPU needs to complete all the tasks.

Example 1

Input:: tasks = ["X","X","Y","Y","X"], n = 2
Output:: 7
Explanation:: One good order is X, Y, idle, X, Y, idle, X.

Example 2

Input:: tasks = ["P","Q","R","P","Q","R"], n = 1
Output:: 6
Explanation:: The order P, Q, R, P, Q, R needs no idle intervals.

Example 3

Input:: tasks = ["M","M","M"], n = 3
Output:: 9
Explanation:: The CPU must stay idle for 3 intervals between two M tasks.

Constraints

1 <= tasks.length <= 10^4
tasks[i] is an uppercase English letter.
0 <= n <= 100

SysRound wrote this statement. A reference solution checks every example.

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Sources · 2 references

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Amazon
Leetcode 621. Task Scheduler
Reported May 2, 2026 · 1 source report
MID_LEVEL
Source snapshot: Nov 12, 2026
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Google
Leetcode 621. Task Scheduler
Reported Jun 11, 2026 · 2 source reports
INTERN, JUNIOR
Source snapshot: Nov 12, 2026
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LinkedIn
Leetcode 621. Task Scheduler
Reported Apr 30, 2026 · 1 source report
MID_LEVEL
Source snapshot: Nov 12, 2026
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NVIDIA
Leetcode 621. Task Scheduler
Reported Mar 4, 2026 · 1 source report
STAFF
Source snapshot: Nov 12, 2026

Problem

You get an array tasks and an integer n. Each task is an uppercase letter, and equal letters are tasks of the same kind.

You can complete the tasks in any order. Return the minimum number of intervals that the CPU needs to complete all the tasks.

Example 1

Input:: tasks = ["X","X","Y","Y","X"], n = 2
Output:: 7
Explanation:: One good order is X, Y, idle, X, Y, idle, X.

Example 2

Input:: tasks = ["P","Q","R","P","Q","R"], n = 1
Output:: 6
Explanation:: The order P, Q, R, P, Q, R needs no idle intervals.

Example 3

Input:: tasks = ["M","M","M"], n = 3
Output:: 9
Explanation:: The CPU must stay idle for 3 intervals between two M tasks.

Constraints

1 <= tasks.length <= 10^4
tasks[i] is an uppercase English letter.
0 <= n <= 100

SysRound wrote this statement. A reference solution checks every example.

Task Scheduler

Problem

Example 1

Example 2

Example 3

Constraints

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Task Scheduler

Problem

Example 1

Example 2

Example 3

Constraints

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