LeetCode 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.

Example 1:

Input: 

plants = [2,2,3,3], capacity = 5

Output: 14

Explanation: 

Start at the river with a full watering can:

- Walk to plant 0 (1 step) and water it. Watering can has 3 units of water. 

- Walk to plant 1 (1 step) and water it. Watering can has 1 unit of water.

- Since you cannot completely water plant 2, walk back to the river to refill (2 steps). 

- Walk to plant 2 (3 steps) and water it. Watering can has 2 units of water. 

- Since you cannot completely water plant 3, walk back to the river to refill (3 steps).

- Walk to plant 3 (4 steps) and water it. Steps needed = 1 + 1 + 2 + 3 + 3 + 4 = 14.

Example 2:

Input: 

plants = [1,1,1,4,2,3], capacity = 4

Output: 30

Explanation: 

Start at the river with a full watering can:

- Water plants 0, 1, and 2 (3 steps).

Return to river (3 steps). 

- Water plant 3 (4 steps). 

Return to river (4 steps). 

- Water plant 4 (5 steps). 

Return to river (5 steps). 

- Water plant 5 (6 steps). 

Steps needed = 3 + 3 + 4 + 4 + 5 + 5 + 6 = 30.

Example 3:

Input: plants = [7,7,7,7,7,7,7], capacity = 8

Output: 49

Explanation: 

You have to refill before watering each plant. Steps needed = 1 + 1 + 2 + 2 + 3 + 3 + 4 + 4 + 5 + 5 + 6 + 6 + 7 = 49.

 路是要走完的，所以这个plants的长度是必须要加上去的，剩下的就是要计算每次折弯的路程即可，只要剩下的水，小于下次要浇水的量，则必须折返，所以加上折返的路程即可。

下面是代码：

Constraints:

• n == plants.length

• 1 <= n <= 1000

• 1 <= plants[i] <= 106

• max(plants[i]) <= capacity <= 109

Runtime: 0 ms, faster than 100.00% of Java online submissions for Watering Plants.

Memory Usage: 42.5 MB, less than 24.56% of Java online submissions for Watering Plants.