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Leetcode 636. Exclusive Time of Functions

24 December 2025
•
3 min read
StackLeetCodeJavaAlgorithms

Description

You have a single-threaded CPU that executes a program with n functions, where each function has a unique ID from 0 to n-1.

The execution follows a call stack pattern:

When a function starts, its ID is pushed onto the stack

When a function ends, its ID is popped from the stack

The function at the top of the stack is the one currently executing

You're given a list of logs where each log entry is formatted as: "{function_id}:{"start" | "end"}:{timestamp}"

Code Example

Here's a Java code:

java
class Solution {
    public int[] exclusiveTime(int n, List<String> logs) {
        int[] ans = new int[n];
       Stack<Integer> stack = new Stack<>();
       int lastTime = 0;
       for(String l : logs) {
        String[] spl = l.split(":");
        if(spl[1].equals("start")){
            if(!stack.isEmpty()) {

                int lastOne = stack.peek();
                ans[lastOne] += Integer.parseInt(spl[2]) - lastTime;
            }

            lastTime = Integer.parseInt(spl[2]);
            stack.push(Integer.parseInt(spl[0]));
        }else{
            int lastOne = stack.pop();
            ans[lastOne] += Integer.parseInt(spl[2]) - lastTime +1;
            lastTime = Integer.parseInt(spl[2])  + 1;
        }
       } 
       return ans;
    }
}