1665. Minimum Initial Energy to Finish Tasks

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.

class Solution {
public:
    int minimumEffort(vector<vector<int>>& A) {
        sort(begin(A), end(A), [](vector<int>&a, vector<int>& b) {
           int ad = a[1] - a[0], bd = b[1] - b[0];
            if(ad == bd)
                return a[1] > b[1];
            return ad > bd;
        });
        
        int res = 0, cur = 0;
        for(auto& t : A) {
            int req = t[1], use = t[0];
            
            if(cur < req) {
                res += (req - cur);
                cur = req - use;
            } else {
                cur = cur - use;
            }
        }
        return res;
    }
};