Exclusive Time of Functions — LeetCode 636 Python Solution

The problem

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

Example

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.

Python solution

class Solution:
    def exclusiveTime(self, n: int, logs: List[str]) -> List[int]:
        stk = []
        ans = [0] * n
        pre = 0
        for log in logs:
            i, op, t = log.split(":")
            i, cur = int(i), int(t)
            if op[0] == "s":
                if stk:
                    ans[stk[-1]] += cur - pre
                stk.append(i)
                pre = cur
            else:
                ans[stk.pop()] += cur - pre + 1
                pre = cur + 1
        return ans

Complexity

Pattern: Stack

When the most recent unresolved thing is the one that matters, use a stack. LeetCode 636. Exclusive Time of Functions is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Stack.

The stack guide has the Python template for the pattern and the 194 LeetCode problems that use it.

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