LeetCode Solution Summary 860. Lemonade Change

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Lituo Programming Problems - Summary of Solutions_Share+Records-CSDN Blog

GitHub synchronous brushing project:

https://github.com/September26/java-algorithms

Link to the original title: Likou

describe:

At the lemonade stand, a glass of lemonade sells for  5 US dollars. Customers line up to buy your product, (in  bills order of bill payment) one drink at a time.

Each customer just buys a glass of lemonade and pays you  5 dollars, 10 dollars, or  20 dollars. You have to give each customer the correct change, which means the net transaction is each customer paying you  5 dollars.

Note that you don't have any change on hand at first.

Give you an array of integers  bills , which  bills[i] is  i the bill paid by the first customer. If you can give each customer correct change, return  true , otherwise return  false .

Example 1:

Input: bills = [5,5,5,10,20]
 Output: true
 Explanation:
 For the first 3 customers, we collect 3 $5 bills in order.
For the 4th customer, we take a $10 bill and give back $5.
With the 5th customer, we return a $10 bill and a $5 bill.
Since all customers got the correct change, we output true.

Example 2:

Input: bills = [5,5,10,10,20]
 Output: false
 Explanation:
For the first 2 customers, we collect 2 $5 bills in sequence.
For the next 2 customers, we take a $10 bill and give back $5.
For the last customer, we can't refund the $15 because we only have two $10 bills right now.
Since not every customer gets the correct change, the answer is false.

hint:

• 1 <= bills.length <= 105
• bills[i] either  5 or  10 _ 20 

Problem-solving ideas:

code:

class Solution {
public:
    bool lemonadeChange(vector<int> &bills)
    {
        int num5 = 0;
        int num10 = 0;
        for (int i = 0; i < bills.size(); i++)
        {
            int bill = bills[i];
            if (bill == 5)
            {
                num5++;
            }
            else if (bill == 10)
            {
                num5--;
                num10++;
            }
            else if (bill == 20)
            {
                if (num10 == 0)
                {
                    num5 = num5 - 3;
                }
                else
                {
                    num5--;
                    num10--;
                }
            }
            if (num10 < 0 || num5 < 0)
            {
                return false;
            }
        }
        return true;
    }
};