Water bottles ii

Math Simulation

78.2% acceptance

Feb 25, 2026

534

102

You are given two integers numBottles and numExchange. numBottles represents the number of full water bottles that you initially have. In one operation, you can perform one of the following operations: Drink any number of full water bottles turning them into empty bottles. Exchange numExchange empty bottles with one full water bottle. Then, increase numExchange by one. Note that you cannot exchange multiple batches of empty bottles for the same value of numExchange. Return the maximum number of water bottles you can drink.

Solution

Rust

Time O(n²)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn max_bottles_drunk(mut num_bottles: i32, mut num_exchange: i32) -> i32 {
    let mut drunk = 0;
    let mut empty = 0;
    while num_bottles > 0 || empty >= num_exchange {
      drunk += num_bottles;
      empty += num_bottles;
      num_bottles = 0;
      while empty >= num_exchange {
        empty -= num_exchange;
        num_exchange += 1;
        num_bottles += 1;
      }
    }
    drunk
  }
}