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/** 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. Return true if and only if you can provide every customer with correct change. Example 1: Input: [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. Example 2: Input: [5,5,10] Output: true Example 3: Input: [10,10] Output: false Example 4: Input: [5,5,10,10,20] Output: false Explanation: From the first two customers in order, we collect two $5 bills. For the next two customers in order, we collect a $10 bill and give back a $5 bill. For the last customer, we can't give change of $15 back because we only have two $10 bills. Since not every customer received correct change, the answer is false. Note: 0 <= bills.length <= 10000 bills[i] will be either 5, 10, or 20. */ public class Lemonade_Change { class Solution { int count5 = 0; int count10 = 0; int count20 = 0; public boolean lemonadeChange(int[] bills) { if (bills == null || bills.length == 0) { return false; } for (int i = 0; i < bills.length; i++) { if (bills[i] == 5) { count5++; } else if (bills[i] == 10) { if (count5 > 0) { count5--; count10++; } else { return false; } } else if (bills[i] == 20) { if (count5 > 0 && count10 > 0) { count5--; count10--; count20++; // not used, but still record it } else if (count5 > 2) { count5 -= 3; } else { return false; } } } return true; } } } ############ class Solution { public boolean lemonadeChange(int[] bills) { int five = 0, ten = 0; for (int v : bills) { if (v == 5) { ++five; } else if (v == 10) { ++ten; --five; } else { if (ten > 0) { --ten; --five; } else { five -= 3; } } if (five < 0) { return false; } } return true; } } -
// OJ: https://leetcode.com/problems/lemonade-change/ // Time: O(N) // Space: O(1) class Solution { public: bool lemonadeChange(vector<int>& bills) { int five = 0, ten = 0; for (auto b : bills) { if (b == 5) { ++five; } else if (b == 10) { if (!five) return false; --five; ++ten; } else { if (five && ten) { --five; --ten; } else if (five >= 3) { five -= 3; } else { return false; } } } return true; } }; -
class Solution: def lemonadeChange(self, bills: List[int]) -> bool: five = ten = 0 for v in bills: if v == 5: five += 1 elif v == 10: ten += 1 five -= 1 else: if ten: ten -= 1 five -= 1 else: five -= 3 if five < 0: return False return True ############ 3 class Solution: def lemonadeChange(self, bills): """ :type bills: List[int] :rtype: bool """ changes = {5:0, 10:0} for bill in bills: if bill == 5: changes[5] += 1 elif bill == 10: if changes[5] == 0: return False else: changes[10] += 1 changes[5] -= 1 elif bill == 20: if changes[10] != 0: if changes[5] == 0: return False else: changes[5] -= 1 changes[10] -= 1 else: if changes[5] < 3: return False else: changes[5] -= 3 return True -
func lemonadeChange(bills []int) bool { five, ten := 0, 0 for _, v := range bills { if v == 5 { five++ } else if v == 10 { ten++ five-- } else { if ten > 0 { ten-- five-- } else { five -= 3 } } if five < 0 { return false } } return true } -
function lemonadeChange(bills: number[]): boolean { let five = 0; let ten = 0; for (let bill of bills) { switch (bill) { case 5: five++; break; case 10: five--; ten++; break; case 20: if (ten !== 0) { ten -= 1; bill -= 10; } five -= bill / 5 - 1; break; } if (five < 0) { return false; } } return true; } -
impl Solution { pub fn lemonade_change(bills: Vec<i32>) -> bool { let (mut five, mut ten) = (0, 0); for bill in bills.iter() { match bill { 5 => { five += 1; } 10 => { five -= 1; ten += 1; } _ => { if ten != 0 { ten -= 1; five -= 1; } else { five -= 3; } } } if five < 0 { return false; } } true } }
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class Solution { public boolean lemonadeChange(int[] bills) { int count5 = 0, count10 = 0; int length = bills.length; for (int i = 0; i < length; i++) { int bill = bills[i]; if (bill == 5) count5++; else if (bill == 10) { count10++; if (count5 == 0) return false; else count5--; } else if (bill == 20) { if (count10 == 0) { if (count5 < 3) return false; else count5 -= 3; } else { if (count5 == 0) return false; else { count10--; count5--; } } } } return true; } } ############ class Solution { public boolean lemonadeChange(int[] bills) { int five = 0, ten = 0; for (int v : bills) { if (v == 5) { ++five; } else if (v == 10) { ++ten; --five; } else { if (ten > 0) { --ten; --five; } else { five -= 3; } } if (five < 0) { return false; } } return true; } } -
// OJ: https://leetcode.com/problems/lemonade-change/ // Time: O(N) // Space: O(1) class Solution { public: bool lemonadeChange(vector<int>& bills) { int five = 0, ten = 0; for (auto b : bills) { if (b == 5) { ++five; } else if (b == 10) { if (!five) return false; --five; ++ten; } else { if (five && ten) { --five; --ten; } else if (five >= 3) { five -= 3; } else { return false; } } } return true; } }; -
class Solution: def lemonadeChange(self, bills: List[int]) -> bool: five = ten = 0 for v in bills: if v == 5: five += 1 elif v == 10: ten += 1 five -= 1 else: if ten: ten -= 1 five -= 1 else: five -= 3 if five < 0: return False return True ############ 3 class Solution: def lemonadeChange(self, bills): """ :type bills: List[int] :rtype: bool """ changes = {5:0, 10:0} for bill in bills: if bill == 5: changes[5] += 1 elif bill == 10: if changes[5] == 0: return False else: changes[10] += 1 changes[5] -= 1 elif bill == 20: if changes[10] != 0: if changes[5] == 0: return False else: changes[5] -= 1 changes[10] -= 1 else: if changes[5] < 3: return False else: changes[5] -= 3 return True -
func lemonadeChange(bills []int) bool { five, ten := 0, 0 for _, v := range bills { if v == 5 { five++ } else if v == 10 { ten++ five-- } else { if ten > 0 { ten-- five-- } else { five -= 3 } } if five < 0 { return false } } return true } -
function lemonadeChange(bills: number[]): boolean { let five = 0; let ten = 0; for (let bill of bills) { switch (bill) { case 5: five++; break; case 10: five--; ten++; break; case 20: if (ten !== 0) { ten -= 1; bill -= 10; } five -= bill / 5 - 1; break; } if (five < 0) { return false; } } return true; } -
impl Solution { pub fn lemonade_change(bills: Vec<i32>) -> bool { let (mut five, mut ten) = (0, 0); for bill in bills.iter() { match bill { 5 => { five += 1; } 10 => { five -= 1; ten += 1; } _ => { if ten != 0 { ten -= 1; five -= 1; } else { five -= 3; } } } if five < 0 { return false; } } true } }