1518. Water Bottles

Problem Link

Description

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There are numBottles water bottles that are initially full of water. You can exchange numExchange empty water bottles from the market with one full water bottle.

The operation of drinking a full water bottle turns it into an empty bottle.

Given the two integers numBottles and numExchange, return the maximum number of water bottles you can drink.

 

Example 1:

Input: numBottles = 9, numExchange = 3
Output: 13
Explanation: You can exchange 3 empty bottles to get 1 full water bottle.
Number of water bottles you can drink: 9 + 3 + 1 = 13.

Example 2:

Input: numBottles = 15, numExchange = 4
Output: 19
Explanation: You can exchange 4 empty bottles to get 1 full water bottle. 
Number of water bottles you can drink: 15 + 3 + 1 = 19.

 

Constraints:

• 1 <= numBottles <= 100
• 2 <= numExchange <= 100

Solution

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Python3

class Solution:
    def numWaterBottles(self, numBottles: int, numExchange: int) -> int:
        res = numBottles
 
        while numBottles >= numExchange:
            numBottles, rem = divmod(numBottles, numExchange)
            res += numBottles
            numBottles += rem
        
        return res

C++

class Solution {
public:
    int numWaterBottles(int numBottles, int numExchange) {
        int res = numBottles;
        
        while (numBottles >= numExchange){
            int remaining = numBottles % numExchange;
            numBottles /= numExchange;
            res += numBottles;
            numBottles += remaining;
        }
           
        return res;
        
    }
};