Check if X can give change to every person in the Queue

Given an array of N integers where Ai denotes the currency of note that the i-th person has. The possible currencies are 5, 10 and 20. All the N people are standing in a queue waiting to buy an ice-cream from X which costs Rs 5. Initially, X has an initial balance of 0. Check if X will be able to provide change to every people who are waiting to buy an ice-cream.

Examples:

Input:a[] = {5, 5, 5, 10, 20}
Output: YES
When the fourth person chance comes to buy an ice-cream, X has three Rs 5
change, hence X gives him 1, and now when the fifth person
comes to buy the ice-cream, X has two Rs 5 and one Rs 10 note, hence he
gives him one Rs 10 and one Rs 5 note.

Input: a[] = {5, 10, 10, 20}
Output: NO

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

The approach is to keep a track of the number of Rs 5 and Rs 10 currencies. Rs 20 currencies will not be used since it is the highest currency that a person can give and thus it cannot be given as a change. Initialize two variables to count Rs 5(fiveCount) and Rs 10(tenCount). If the person has a Rs 10 currency and fiveCount > 0, then decrease fiveCount and increase tenCount. If X does not have Rs 5, then X cannot give the person the required change. If the person has 5\$ note, increase fiveCount by one. If the person has a Rs 20, then three conditions will be:

• If fiveCount > 0 and tencount > 0, decrease both.
• else if, fiveCount >= 3, decrease fivecount by three.
• else, return false.

If all the person in the queue gets the change, then print “YES” else print “NO”.

Below is the implementation of the above idea.

C++

 `// C++ program to check whether X can give change ` `// to every person in the Queue ` `#include ` `using` `namespace` `std; ` ` `  `// Function to check if every person will ` `// get the change from X ` `int` `isChangeable(``int` `notes[], ``int` `n) ` `{ ` `    ``// To count the 5\$ and 10& notes ` `    ``int` `fiveCount = 0; ` `    ``int` `tenCount = 0; ` ` `  `    ``// Serve the customer in order ` `    ``for` `(``int` `i = 0; i < n; i++) { ` ` `  `        ``// Increase the number of 5\$ note by one ` `        ``if` `(notes[i] == 5) ` `            ``fiveCount++; ` `        ``else` `if` `(notes[i] == 10) { ` ` `  `            ``// decrease the number of note 5\$ and ` `            ``// increase 10\$ note by one ` `            ``if` `(fiveCount > 0) { ` `                ``fiveCount--; ` `                ``tenCount++; ` `            ``} ` `            ``else` `                ``return` `0; ` `        ``} ` `        ``else` `{ ` ` `  `            ``// decrease 5\$ and 10\$ note by one ` `            ``if` `(fiveCount > 0 && tenCount > 0) { ` `                ``fiveCount--; ` `                ``tenCount--; ` `            ``} ` ` `  `            ``// decrease 5\$ note by three ` `            ``else` `if` `(fiveCount >= 3) { ` `                ``fiveCount -= 3; ` `            ``} ` `            ``else` `                ``return` `0; ` `        ``} ` `    ``} ` ` `  `    ``return` `1; ` `} ` `// Driver Code ` `int` `main() ` `{ ` `    ``// queue of customers with available notes. ` `    ``int` `a[] = { 5, 5, 5, 10, 20 }; ` `    ``int` `n = ``sizeof``(a) / ``sizeof``(a[0]); ` ` `  `    ``// Calling function ` `    ``if` `(isChangeable(a, n)) ` `        ``cout << ``"YES"``; ` `    ``else` `        ``cout << ``"NO"``; ` ` `  `    ``return` `0; ` `} `

Java

 `// Java program to check  ` `// whether X can give  ` `// change to every person  ` `// in the Queue ` `import` `java.io.*; ` ` `  `class` `GFG  ` `{ ` `     `  `// Function to check if ` `// every person will ` `// get the change from X ` `static` `int` `isChangeable(``int` `notes[],  ` `                        ``int` `n) ` `{ ` `    ``// To count the 5\$ ` `    ``// and 10& notes ` `    ``int` `fiveCount = ``0``; ` `    ``int` `tenCount = ``0``; ` ` `  `    ``// Serve the customer  ` `    ``// in order ` `    ``for` `(``int` `i = ``0``; i < n; i++)  ` `    ``{ ` ` `  `        ``// Increase the number ` `        ``// of 5\$ note by one ` `        ``if` `(notes[i] == ``5``) ` `            ``fiveCount++; ` `        ``else` `if` `(notes[i] == ``10``)  ` `        ``{ ` ` `  `            ``// decrease the number  ` `            ``// of note 5\$ and  ` `            ``// increase 10\$ note by one ` `            ``if` `(fiveCount > ``0``)  ` `            ``{ ` `                ``fiveCount--; ` `                ``tenCount++; ` `            ``} ` `            ``else` `                ``return` `0``; ` `        ``} ` `        ``else`  `        ``{ ` ` `  `            ``// decrease 5\$ and  ` `            ``// 10\$ note by one ` `            ``if` `(fiveCount > ``0` `&&  ` `                ``tenCount > ``0``)  ` `            ``{ ` `                ``fiveCount--; ` `                ``tenCount--; ` `            ``} ` ` `  `            ``// decrease 5\$  ` `            ``// note by three ` `            ``else` `if` `(fiveCount >= ``3``)  ` `            ``{ ` `                ``fiveCount -= ``3``; ` `            ``} ` `            ``else` `                ``return` `0``; ` `        ``} ` `    ``} ` ` `  `    ``return` `1``; ` `} ` ` `  `// Driver Code ` `public` `static` `void` `main (String[] args)  ` `{ ` `     `  `// queue of customers  ` `// with available notes. ` `int` `a[] = {``5``, ``5``, ``5``, ``10``, ``20``}; ` `int` `n = a.length; ` ` `  `// Calling function ` `if` `(isChangeable(a, n) > ``0``) ` `    ``System.out.print(``"YES"``); ` `else` `    ``System.out.print(``"NO"``); ` `} ` `} ` ` `  `// This code is contributed  ` `// by anuj_67. `

Python3

# Python program to check whether X can
# give change to every person in the Queue

# Function to check if every person
# will get the change from X
def isChangeable(notes, n):

# To count the 5\$ and 10& notes
fiveCount = 0
tenCount = 0

# Serve the customer in order
for i in range(n):

# Increase the number of 5\$ note by one
if (notes[i] == 5):
fiveCount += 1
elif(notes[i] == 10):

# decrease the number of note 5\$
# and increase 10\$ note by one
if (fiveCount > 0):
fiveCount -= 1
tenCount += 1
else:
return 0
else:

# decrease 5\$ and 10\$ note by one
if (fiveCount > 0 and tenCount > 0):
fiveCount -= 1
tenCount -= 1

# decrease 5\$ note by three
elif (fiveCount >= 3):
fiveCount -= 3
else:
return 0
return 1

# Driver Code

# queue of customers with available notes.
a = [5, 5, 5, 10, 20 ]
n = len(a)

# Calling function
if (isChangeable(a, n)):
print(“YES”)
else:
print(“NO”)

# This code is contributed by PrinciRaj1992

C#

 `// C# program to check  ` `// whether X can give  ` `// change to every person  ` `// in the Queue ` `using` `System; ` ` `  `class` `GFG  ` `{ ` `     `  `// Function to check if ` `// every person will ` `// get the change from X ` `static` `int` `isChangeable(``int` `[]notes,  ` `                        ``int` `n) ` `{ ` `    ``// To count the 5\$ ` `    ``// and 10& notes ` `    ``int` `fiveCount = 0; ` `    ``int` `tenCount = 0; ` ` `  `    ``// Serve the customer  ` `    ``// in order ` `    ``for` `(``int` `i = 0; i < n; i++)  ` `    ``{ ` ` `  `        ``// Increase the number ` `        ``// of 5\$ note by one ` `        ``if` `(notes[i] == 5) ` `            ``fiveCount++; ` `        ``else` `if` `(notes[i] == 10)  ` `        ``{ ` ` `  `            ``// decrease the number  ` `            ``// of note 5\$ and  ` `            ``// increase 10\$ note by one ` `            ``if` `(fiveCount > 0)  ` `            ``{ ` `                ``fiveCount--; ` `                ``tenCount++; ` `            ``} ` `            ``else` `                ``return` `0; ` `        ``} ` `        ``else` `        ``{ ` ` `  `            ``// decrease 5\$ and  ` `            ``// 10\$ note by one ` `            ``if` `(fiveCount > 0 &&  ` `                ``tenCount > 0)  ` `            ``{ ` `                ``fiveCount--; ` `                ``tenCount--; ` `            ``} ` ` `  `            ``// decrease 5\$  ` `            ``// note by three ` `            ``else` `if` `(fiveCount >= 3)  ` `            ``{ ` `                ``fiveCount -= 3; ` `            ``} ` `            ``else` `                ``return` `0; ` `        ``} ` `    ``} ` ` `  `    ``return` `1; ` `} ` ` `  `// Driver Code ` `public` `static` `void` `Main ()  ` `{ ` `     `  `// queue of customers  ` `// with available notes. ` `int` `[]a = {5, 5, 5, 10, 20}; ` `int` `n = a.Length; ` ` `  `// Calling function ` `if` `(isChangeable(a, n) > 0) ` `    ``Console.WriteLine(``"YES"``); ` `else` `    ``Console.WriteLine(``"NO"``); ` `} ` `} ` ` `  `// This code is contributed  ` `// by anuj_67. `

Output:

```YES
```