> ## Documentation Index
> Fetch the complete documentation index at: https://leetcode-py.wisl.dev/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> leetcode-py is a Python LeetCode practice environment generator with one CLI: lcpy. It is not a service or platform.
> Each problem is a directory under leetcode/ with README.md, solution.py, test_solution.py, helpers.py, and playground.ipynb. lcpy gen creates them from JSON templates bundled with the package.
> Examples are backed by tests; copy them verbatim.

# Exclusive Time of Functions Python Solution

> Tested Python solution for LeetCode 636 with 16 pytest cases. Generate a practice environment with lcpy.

LeetCode 636, [Medium](/catalog/medium). Topics: [Array](/catalog/topics/array), [Stack](/catalog/topics/stack). [View on LeetCode](https://leetcode.com/problems/exclusive-time-of-functions/description/).

Generate this problem as a practice environment: tested reference solution, 16 [parametrized pytest cases](/practice/testing), and a playground notebook:

```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
lcpy gen -n 636   # by problem number
lcpy gen -s exclusive_time_of_functions   # by problem name
```

## Problem

On a single-threaded CPU, we execute a program containing `n` functions. Each function has a unique ID between `0` and `n - 1`.

Function calls are stored in a call stack: when a function call starts, its ID is pushed onto the stack, and when a function call ends, its ID is popped off the stack. The function whose ID is at the top of the stack is the current function being executed. Each time a function starts or ends, we write a log with the ID, whether it started or ended, and the timestamp.

You are given a list `logs`, where `logs[i]` represents the `i-th` log message formatted as a string `"{function_id}:\"start\" | \"end\":{timestamp}"`. For example, `"0:start:3"` means a function call with function ID 0 started at the beginning of timestamp 3, and `"1:end:2"` means a function call with function ID 1 ended at the end of timestamp 2. Note that a function can be called multiple times, possibly recursively.

A function's exclusive time is the sum of execution times for all function calls in the program. For example, if a function is called twice, one call executing for 2 time units and another call executing for 1 time unit, the exclusive time is `2 + 1 = 3`.

Return the exclusive time of each function in an array, where the value at the `i-th` index represents the exclusive time for the function with ID `i`.

### Examples

![Example 1](https://assets.leetcode.com/uploads/2019/04/05/diag1b.png)

```
Input: n = 2, logs = ["0:start:0","1:start:2","1:end:5","0:end:6"]
Output: [3,4]
Explanation:
Function 0 starts at the beginning of time 0, then it executes 2 for units of time and reaches the end of time 1.
Function 1 starts at the beginning of time 2, executes for 4 units of time, and ends at the end of time 5.
Function 0 resumes execution at the beginning of time 6 and executes for 1 unit of time.
So function 0 spends 2 + 1 = 3 units of total time executing, and function 1 spends 4 units of total time executing.
```

```
Input: n = 1, logs = ["0:start:0","0:start:2","0:end:5","0:start:6","0:end:6","0:end:7"]
Output: [8]
Explanation:
Function 0 starts at the beginning of time 0, executes for 2 units of time, and recursively calls itself.
Function 0 (recursive call) starts at the beginning of time 2 and executes for 4 units of time.
Function 0 (initial call) resumes execution then immediately calls itself again.
Function 0 (2nd recursive call) starts at the beginning of time 6 and executes for 1 unit of time.
Function 0 (initial call) resumes execution at the beginning of time 7 and executes for 1 unit of time.
So function 0 spends 2 + 4 + 1 + 1 = 8 units of total time executing.
```

```
Input: n = 2, logs = ["0:start:0","0:start:2","0:end:5","1:start:6","1:end:6","0:end:7"]
Output: [7,1]
Explanation:
Function 0 starts at the beginning of time 0, executes for 2 units of time, and recursively calls itself.
Function 0 (recursive call) starts at the beginning of time 2 and executes for 4 units of time.
Function 0 (initial call) resumes execution then immediately calls function 1.
Function 1 starts at the beginning of time 6, executes 1 unit of time, and ends at the end of time 6.
Function 0 resumes execution at the beginning of time 7 and executes for 1 unit of time.
So function 0 spends 2 + 4 + 1 = 7 units of total time executing, and function 1 spends 1 unit of total time executing.
```

### Constraints

* 1 \<= n \<= 100
* 2 \<= logs.length \<= 500
* 0 \<= function\_id \< n
* 0 \<= timestamp \<= 10^9
* No two start events will happen at the same timestamp.
* No two end events will happen at the same timestamp.
* Each function has an "end" log for each "start" log.

## Solution

Reference implementation from [solution.py on GitHub](https://github.com/wislertt/leetcode-py/blob/main/leetcode/exclusive_time_of_functions/solution.py), full suite in [test\_solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/exclusive_time_of_functions/test_solution.py):

```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
class Solution:
    # Time: O(L) where L is the number of log entries
    # Space: O(n) for the call stack
    def exclusive_time(self, n: int, logs: list[str]) -> list[int]:
        result = [0] * n
        stack: list[int] = []
        prev = 0
        for log in logs:
            func_id_s, kind, ts_s = log.split(":")
            func_id, ts = int(func_id_s), int(ts_s)
            if kind == "start":
                if stack:
                    result[stack[-1]] += ts - prev
                stack.append(func_id)
                prev = ts
            else:
                result[stack.pop()] += ts - prev + 1
                prev = ts + 1
        return result
```

## Complexity

| Time | Space |
| - | - |
| O(L) where L is the number of log entries | O(n) for the call stack |

## Tags


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