Formatted question description: https://leetcode.ca/all/1518.html

# 1518. Water Bottles (Easy)

Given `numBottles`

full water bottles, you can exchange `numExchange`

empty water bottles for one full water bottle.

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

Return the **maximum** number of water bottles you can drink.

**Example 1:**

Input:numBottles = 9, numExchange = 3Output:13Explanation: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 = 4Output:19Explanation:You can exchange 4 empty bottles to get 1 full water bottle. Number of water bottles you can drink: 15 + 3 + 1 = 19.

**Example 3:**

Input:numBottles = 5, numExchange = 5Output:6

**Example 4:**

Input:numBottles = 2, numExchange = 3Output:2

**Constraints:**

`1 <= numBottles <= 100`

`2 <= numExchange <= 100`

**Related Topics**:

Greedy

## Solution 1.

```
// OJ: https://leetcode.com/problems/water-bottles/
// Time: O(log_exchange^bottle)
// Space: O(1)
class Solution {
public:
int numWaterBottles(int bottle, int exchange) {
int ans = 0, empty = 0;
while (bottle) {
ans += bottle;
empty += bottle;
int ex = empty / exchange;
empty -= ex * exchange;
bottle = ex;
}
return ans;
}
};
```

Java

```
class Solution {
public int numWaterBottles(int numBottles, int numExchange) {
int total = 0;
int water = numBottles, empty = 0;
while (water > 0) {
total += water;
empty += water;
water = 0;
int exchange = empty / numExchange;
water += exchange;
empty -= numExchange * exchange;
}
return total;
}
}
```