1665. Minimum Initial Energy to Finish Tasks

Description

You are given an array tasks where tasks[i] = [actuali, minimumi]:

  • actuali is the actual amount of energy you spend to finish the ith task.
  • minimumi is the minimum amount of energy you require to begin the ith task.

For example, if the task is [10, 12] and your current energy is 11, you cannot start this task. However, if your current energy is 13, you can complete this task, and your energy will be 3 after finishing it.

You can finish the tasks in any order you like.

Return the minimum initial amount of energy you will need to finish all the tasks.

 

Example 1:

Input: tasks = [[1,2],[2,4],[4,8]]
Output: 8
Explanation:
Starting with 8 energy, we finish the tasks in the following order:
    - 3rd task. Now energy = 8 - 4 = 4.
    - 2nd task. Now energy = 4 - 2 = 2.
    - 1st task. Now energy = 2 - 1 = 1.
Notice that even though we have leftover energy, starting with 7 energy does not work because we cannot do the 3rd task.

Example 2:

Input: tasks = [[1,3],[2,4],[10,11],[10,12],[8,9]]
Output: 32
Explanation:
Starting with 32 energy, we finish the tasks in the following order:
    - 1st task. Now energy = 32 - 1 = 31.
    - 2nd task. Now energy = 31 - 2 = 29.
    - 3rd task. Now energy = 29 - 10 = 19.
    - 4th task. Now energy = 19 - 10 = 9.
    - 5th task. Now energy = 9 - 8 = 1.

Example 3:

Input: tasks = [[1,7],[2,8],[3,9],[4,10],[5,11],[6,12]]
Output: 27
Explanation:
Starting with 27 energy, we finish the tasks in the following order:
    - 5th task. Now energy = 27 - 5 = 22.
    - 2nd task. Now energy = 22 - 2 = 20.
    - 3rd task. Now energy = 20 - 3 = 17.
    - 1st task. Now energy = 17 - 1 = 16.
    - 4th task. Now energy = 16 - 4 = 12.
    - 6th task. Now energy = 12 - 6 = 6.

 

Constraints:

  • 1 <= tasks.length <= 105
  • 1 <= actual​i <= minimumi <= 104

Solutions

Solution 1

Python Code
1
2
3
4
5
6
7
8
9

class Solution:
    def minimumEffort(self, tasks: List[List[int]]) -> int:
        ans = cur = 0
        for a, m in sorted(tasks, key=lambda x: x[0] - x[1]):
            if cur < m:
                ans += m - cur
                cur = m
            cur -= a
        return ans

Java Code
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15

class Solution {
    public int minimumEffort(int[][] tasks) {
        Arrays.sort(tasks, (a, b) -> a[0] - b[0] - (a[1] - b[1]));
        int ans = 0, cur = 0;
        for (var task : tasks) {
            int a = task[0], m = task[1];
            if (cur < m) {
                ans += m - cur;
                cur = m;
            }
            cur -= a;
        }
        return ans;
    }
}

C++ Code
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16

class Solution {
public:
    int minimumEffort(vector<vector<int>>& tasks) {
        sort(tasks.begin(), tasks.end(), [&](const auto& a, const auto& b) { return a[0] - a[1] < b[0] - b[1]; });
        int ans = 0, cur = 0;
        for (auto& task : tasks) {
            int a = task[0], m = task[1];
            if (cur < m) {
                ans += m - cur;
                cur = m;
            }
            cur -= a;
        }
        return ans;
    }
};

Go Code
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13

func minimumEffort(tasks [][]int) (ans int) {
	sort.Slice(tasks, func(i, j int) bool { return tasks[i][0]-tasks[i][1] < tasks[j][0]-tasks[j][1] })
	cur := 0
	for _, task := range tasks {
		a, m := task[0], task[1]
		if cur < m {
			ans += m - cur
			cur = m
		}
		cur -= a
	}
	return
}

TypeScript Code
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13

function minimumEffort(tasks: number[][]): number {
    tasks.sort((a, b) => a[0] - a[1] - (b[0] - b[1]));
    let ans = 0;
    let cur = 0;
    for (const [a, m] of tasks) {
        if (cur < m) {
            ans += m - cur;
            cur = m;
        }
        cur -= a;
    }
    return ans;
}