2432. The Employee That Worked on the Longest Task

Description

There are n employees, each with a unique id from 0 to n - 1.

You are given a 2D integer array logs where logs[i] = [idi, leaveTimei] where:

  • idi is the id of the employee that worked on the ith task, and
  • leaveTimei is the time at which the employee finished the ith task. All the values leaveTimei are unique.

Note that the ith task starts the moment right after the (i - 1)th task ends, and the 0th task starts at time 0.

Return the id of the employee that worked the task with the longest time. If there is a tie between two or more employees, return the smallest id among them.

 

Example 1:

Input: n = 10, logs = [[0,3],[2,5],[0,9],[1,15]]
Output: 1
Explanation: 
Task 0 started at 0 and ended at 3 with 3 units of times.
Task 1 started at 3 and ended at 5 with 2 units of times.
Task 2 started at 5 and ended at 9 with 4 units of times.
Task 3 started at 9 and ended at 15 with 6 units of times.
The task with the longest time is task 3 and the employee with id 1 is the one that worked on it, so we return 1.

Example 2:

Input: n = 26, logs = [[1,1],[3,7],[2,12],[7,17]]
Output: 3
Explanation: 
Task 0 started at 0 and ended at 1 with 1 unit of times.
Task 1 started at 1 and ended at 7 with 6 units of times.
Task 2 started at 7 and ended at 12 with 5 units of times.
Task 3 started at 12 and ended at 17 with 5 units of times.
The tasks with the longest time is task 1. The employee that worked on it is 3, so we return 3.

Example 3:

Input: n = 2, logs = [[0,10],[1,20]]
Output: 0
Explanation: 
Task 0 started at 0 and ended at 10 with 10 units of times.
Task 1 started at 10 and ended at 20 with 10 units of times.
The tasks with the longest time are tasks 0 and 1. The employees that worked on them are 0 and 1, so we return the smallest id 0.

 

Constraints:

  • 2 <= n <= 500
  • 1 <= logs.length <= 500
  • logs[i].length == 2
  • 0 <= idi <= n - 1
  • 1 <= leaveTimei <= 500
  • idi != idi+1
  • leaveTimei are sorted in a strictly increasing order.

Solutions

Solution 1: Direct Traversal

We use a variable $last$ to record the end time of the last task, a variable $mx$ to record the longest working time, and a variable $ans$ to record the employee with the longest working time and the smallest $id$. Initially, all three variables are $0$.

Next, we traverse the array $logs$. For each employee, we subtract the end time of the last task from the time the employee completes the task to get the working time $t$ of this employee. If $mx$ is less than $t$, or $mx$ equals $t$ and the $id$ of this employee is less than $ans$, then we update $mx$ and $ans$. Then we update $last$ to be the end time of the last task plus $t$. Continue to traverse until the entire array is traversed.

Finally, return the answer $ans$.

The time complexity is $O(n)$, where $n$ is the length of the array $logs$. The space complexity is $O(1)$.

Python Code
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class Solution:
    def hardestWorker(self, n: int, logs: List[List[int]]) -> int:
        last = mx = ans = 0
        for uid, t in logs:
            t -= last
            if mx < t or (mx == t and ans > uid):
                ans, mx = uid, t
            last += t
        return ans

Java Code
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class Solution {
    public int hardestWorker(int n, int[][] logs) {
        int ans = 0;
        int last = 0, mx = 0;
        for (int[] log : logs) {
            int uid = log[0], t = log[1];
            t -= last;
            if (mx < t || (mx == t && ans > uid)) {
                ans = uid;
                mx = t;
            }
            last += t;
        }
        return ans;
    }
}

C++ Code
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class Solution {
public:
    int hardestWorker(int n, vector<vector<int>>& logs) {
        int ans = 0, mx = 0, last = 0;
        for (auto& log : logs) {
            int uid = log[0], t = log[1];
            t -= last;
            if (mx < t || (mx == t && ans > uid)) {
                mx = t;
                ans = uid;
            }
            last += t;
        }
        return ans;
    }
};

Go Code
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func hardestWorker(n int, logs [][]int) (ans int) {
	var mx, last int
	for _, log := range logs {
		uid, t := log[0], log[1]
		t -= last
		if mx < t || (mx == t && uid < ans) {
			mx = t
			ans = uid
		}
		last += t
	}
	return
}

TypeScript Code
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function hardestWorker(n: number, logs: number[][]): number {
    let [ans, mx, last] = [0, 0, 0];
    for (let [uid, t] of logs) {
        t -= last;
        if (mx < t || (mx == t && ans > uid)) {
            ans = uid;
            mx = t;
        }
        last += t;
    }
    return ans;
}

Rust Code
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impl Solution {
    pub fn hardest_worker(n: i32, logs: Vec<Vec<i32>>) -> i32 {
        let mut res = 0;
        let mut max = 0;
        let mut pre = 0;
        for log in logs.iter() {
            let t = log[1] - pre;
            if t > max || (t == max && res > log[0]) {
                res = log[0];
                max = t;
            }
            pre = log[1];
        }
        res
    }
}

C Code
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#define min(a, b) (((a) < (b)) ? (a) : (b))

int hardestWorker(int n, int** logs, int logsSize, int* logsColSize) {
    int res = 0;
    int max = 0;
    int pre = 0;
    for (int i = 0; i < logsSize; i++) {
        int t = logs[i][1] - pre;
        if (t > max || (t == max && res > logs[i][0])) {
            res = logs[i][0];
            max = t;
        }
        pre = logs[i][1];
    }
    return res;
}

Solution 2

Rust Code
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impl Solution {
    pub fn hardest_worker(n: i32, logs: Vec<Vec<i32>>) -> i32 {
        let mut ans = 0;
        let mut mx = 0;
        let mut last = 0;

        for log in logs {
            let uid = log[0];
            let t = log[1];

            let diff = t - last;
            last = t;

            if diff > mx || (diff == mx && uid < ans) {
                ans = uid;
                mx = diff;
            }
        }

        ans
    }
}