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);        // 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

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