[LeetCode]636. Exclusive Time of Functions

https://leetcode.com/problems/exclusive-time-of-functions/#/description

给一个log数组，表示非抢占式CPU调用function的情况。格式为id:start or end:time

求每个func占用cpu的总时间

用stack保存当前还在调用栈内的func的id，pre记录前序时间。遇到start要push进入stack，遇到end要pop

public class Solution {
    public int[] exclusiveTime(int n, List<String> logs) {
        int[] res = new int[n];
        Stack<Integer> stack = new Stack();
        int pre = 0;
        for (String log : logs) {
            String[] arr = log.split(":");
            if (arr[1].equals("start")) {
                if (!stack.isEmpty()) {
                    res[stack.peek()] += Integer.parseInt(arr[2]) - pre;
                }
                stack.push(Integer.parseInt(arr[0]));
                pre = Integer.parseInt(arr[2]);
            } else {
                res[stack.pop()] += Integer.parseInt(arr[2]) - pre + 1;
                pre = Integer.parseInt(arr[2]) + 1;
            }
        }
        return res;
    }
}