3100. Water Bottles II

Medium

題目描述

Description

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. For example, if numBottles == 3 and numExchange == 1, you cannot exchange 3 empty water bottles for 3 full bottles.

Return the maximum number of water bottles you can drink.

Example 1:

Input: numBottles = 13, numExchange = 6
Output: 15
Explanation: The table above shows the number of full water bottles, empty water bottles, the value of numExchange, and the number of bottles drunk.

Example 2:

Input: numBottles = 10, numExchange = 3
Output: 13
Explanation: The table above shows the number of full water bottles, empty water bottles, the value of numExchange, and the number of bottles drunk.

Constraints:

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

解答

Solution

/**
 * @param {number} numBottles
 * @param {number} numExchange
 * @return {number}
 */
var maxBottlesDrunk = function (numBottles, numExchange) {
  let bottlesDrunk = 0;
  let emptyBottles = 0;

  while (numBottles > 0) {
    bottlesDrunk += numBottles;
    emptyBottles += numBottles;
    numBottles = 0;

    while (emptyBottles >= numExchange) {
      emptyBottles -= numExchange;
      numExchange++;
      numBottles++;
    }
  }

  return bottlesDrunk;
};

解題思路

與 1518. Water Bottles 大致相同，不同之處在於

1. 同一值的 numExchange 只能用於交換一次
2. 使用 numExchange 交換後，numExchange 要 +1

照此更新邏輯就是答案了。

while (emptyBottles >= numExchange) {
  emptyBottles -= numExchange;
  numExchange++;
  numBottles++; //  同一值的 numExchange 只能用於交換一次，所以是++
}

心得

先完成上題再做這題的話會簡單不少，用 1518. Water Bottles 改一下就是答案了。