Leetcode 860 - Lemonade change

Note:

  • What I thought was naive is what most ppl did.
  • Try to give changes with bigger values.
  • Use an array to store how many bills we have for each value.

At a lemonade stand, each lemonade costs $5. Customers are standing in a queue to buy from you, and order one at a time (in the order specified by bills). Each customer will only buy one lemonade and pay with either a $5, $10, or $20 bill. You must provide the correct change to each customer so that the net transaction is that the customer pays $5.

Note that you don’t have any change in hand at first.

Given an integer array bills where bills[i] is the bill the ith customer pays, return true if you can provide every customer with correct change, or false otherwise.

Example

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Input: bills = [5,5,5,10,20]
Output: true
Explanation:
From the first 3 customers, we collect three $5 bills in order.
From the fourth customer, we collect a $10 bill and give back a $5.
From the fifth customer, we give a $10 bill and a $5 bill.
Since all customers got correct change, we output true.
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/**
* @param {number[]} bills
* @return {boolean}
*/
var lemonadeChange = function(bills) {
let cash = [0,0,0];
for (let i = 0; i < bills.length; i++) {
if (bills[i] === 20) {
if (cash[1] >= 1 && cash[0] >= 1) {
cash[1]--;
cash[0]--;
cash[2]++;
continue;
} else if (cash[0] >= 3) {
cash[0] -= 3;
cash[2]++;
continue;
}
return false;
} else if (bills[i] === 10) {
if (cash[0] >= 1) {
cash[0]--;
cash[1]++;
continue;
}
return false;
} else if (bills[i] === 5) {
cash[0]++;
continue;
}
}
return true;
};