# Minimum Initial Energy to Finish Tasks

This page explains Java solution to problem `Minimum Initial Energy to Finish Tasks` using `Greedy` algorithm.

## Problem Statement

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.

## Solution

If you have any suggestions in below code, please create a pull request by clicking here.
``````
package com.vc.hard;

import java.util.Arrays;
import java.util.Comparator;

class MinimumInitialEnergyToFinishTasks {
public int minimumEffort(int[][] tasks) {
Arrays.sort(tasks, new Comparator<int[]>(){
public int compare(int[] x, int[] y) {
return Integer.compare(x - x, y - y);
}
});

int res = 0;
for(int[] task: tasks) {
res = Math.max(res + task, task);
}
return res;
}
}
``````

## Time Complexity

O(N log N) Where
N is total number of elements in an input array

O(1)