2079. Watering Plants

You want to water n plants in your garden with a watering can. The plants are arranged in a row and are labeled from 0 to n - 1 from left to right where the ith plant is located at x = i. There is a river at x = -1 that you can refill your watering can at.

Each plant needs a specific amount of water. You will water the plants in the following way:

• Water the plants in order from left to right.
• After watering the current plant, if you do not have enough water to completely water the next plant, return to the river to fully refill the watering can.
• You cannot refill the watering can early.

You are initially at the river (i.e., x = -1). It takes one step to move one unit on the x-axis.

Given a 0-indexed integer array plants of n integers, where plants[i] is the amount of water the ith plant needs, and an integer capacity representing the watering can capacity, return the number of steps needed to water all the plants.

class Solution {
public:
    int wateringPlants(vector<int>& A, int capacity) {
        int res = 0, now = capacity;
        for(int i = 0; i < A.size(); i++) {
            res += 1;
            if(now < A[i]) {
                res += 2 * i;
                now = capacity;
            }
            now -= A[i];
        }
        return res;
    }
};