Minimum Initial Energy to Finish Tasks

arraygreedysorting

Problem Statement

You are given an array tasks where tasks[i] = [actual _i , minimum _i ] :

actual _i is the actual amount of energy you spend to finish the i ^th task.

minimum _i is the minimum amount of energy you require to begin the i ^th 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 .

Examples

Example 1

Input: tasks = [[1,2],[2,4],[4,8]]
Output: 8
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
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
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 <= 10 ^5

1 <= actual _i <= minimum _i <= 10 ^4

😤

Hard

Difficulty

Topic Info

ModuleDSA

CategoryArray

Sub-topicGreedy