#include <cs50.h> 
#include <stdio.h> 
#include <math.h> 
  
int main(void) 
{ 
    // ichangeD is equal to the change in dollars 
    float ichangeD; 
      
    //ichangeC is equal to the change in cents 
    int ichangeC; 
      
    do
    { 
        // ask for user the change and covert it to cents 
        printf("What is the amount of spare change owed (in dollars)?\n"); 
        ichangeD = GetFloat(); 
        ichangeC = round(ichangeD * 100); 
           
    } 
    while(ichangeD < 0); 
      
    printf("So %.2f dollars or %.0d cents are needed!\n", ichangeD, ichangeC); 
      
    // declare variables of different possible monetary values
    int DaCount = 0; 
    int DaDCount = 0; 
    int ldollars = 0; 
    int gdollars = 0; 
    int hdollars = 0; 
    int jdollars = 0; 
    int quarters = 0; 
    int dimes = 0; 
    int nickles = 0; 
    int pennies = 0; 
      
    while(ichangeC % 2000 != ichangeC) 
    { 
        jdollars++; 
        DaDCount++; 
        ichangeC = ichangeC - 2000; 
    } 
      
    printf("%d twenty dollar bills needed\n", jdollars);      
                
      
    // since remainder of something less that a certain number is that number that you 
    // trying to divide, use a while loop to do this until something happens
    // then move on to the next monetary value while keeping track of count of money
    while(ichangeC % 1000 != ichangeC) 
    { 
        hdollars++; 
        DaDCount++; 
        ichangeC = ichangeC - 1000; 
    } 
      
    printf("%d ten dollar bills needed\n", hdollars);   
      
    while(ichangeC % 500 != ichangeC) 
    { 
        ldollars++; 
        DaDCount++; 
        ichangeC = ichangeC - 500; 
    } 
            
    printf("%d five dollar bills needed\n", ldollars);   
      
    while(ichangeC % 100 != ichangeC) 
    { 
        gdollars++; 
        DaDCount++; 
        ichangeC = ichangeC - 100;  
    } 
      
    printf("%d one dollar bills needed\n", gdollars); 
      
    printf("%d bills in total needed\n", DaDCount); 
      
    while(ichangeC % 25 != ichangeC) 
    { 
        quarters ++; 
        DaCount++; 
        ichangeC = ichangeC - 25; 
    } 
      
    printf("%d quarters needed\n", quarters); 
      
    while(ichangeC % 10 != ichangeC) 
    { 
        dimes++; 
        DaCount++; 
        ichangeC = ichangeC - 10; 
    } 
      
    printf("%d dimes needed\n", dimes); 
     
    while(ichangeC % 5 != ichangeC) 
    { 
        nickles++; 
        DaCount++; 
        ichangeC = ichangeC - 5; 
    } 
  
    printf("%d nickles needed\n", nickles); 
   
    while(ichangeC % 1 != ichangeC) 
    { 
        pennies++; 
        DaCount++; 
        ichangeC = ichangeC - 1; 
    } 
      
    printf("%d pennies needed\n", pennies); 
      
    printf("%d coins in total are needed!\n", DaCount); 
      
}

#include <cs50.h> 
#include <stdio.h> 
#include <math.h> 
  
int main(void) 
{ 
    // ichangeD is equal to the change in dollars 
    float ichangeD; 
      
    //ichangeC is equal to the change in cents 
    int ichangeC; 
      
    do
    { 
        printf("What is the amount of spare change owed (in dollars)?\n"); 
        ichangeD = GetFloat(); 
        ichangeC = round(ichangeD * 100); 
           
    } 
    while(ichangeD < 0); 
      
    printf("So %.2f dollars or %.0d cents are needed!\n", ichangeD, ichangeC); 
      
    int DaCount = 0; 
    int DaDCount = 0; 
    int ldollars = 0; 
    int gdollars = 0; 
    int hdollars = 0; 
    int jdollars = 0; 
    int quarters = 0; 
    int dimes = 0; 
    int nickles = 0; 
    int pennies = 0; 
      
    while(ichangeC % 2000 != ichangeC) 
    { 
        jdollars++; 
        DaDCount++; 
        ichangeC = ichangeC - 2000; 
    } 
      
    printf("%d twenty dollar bills needed\n", jdollars);      
                
      
    while(ichangeC % 1000 != ichangeC) 
    { 
        hdollars++; 
        DaDCount++; 
        ichangeC = ichangeC - 1000; 
    } 
      
    printf("%d ten dollar bills needed\n", hdollars);   
      
    while(ichangeC % 500 != ichangeC) 
    { 
        ldollars++; 
        DaDCount++; 
        ichangeC = ichangeC - 500; 
    } 
            
    printf("%d five dollar bills needed\n", ldollars);   
      
    while(ichangeC % 100 != ichangeC) 
    { 
        gdollars++; 
        DaDCount++; 
        ichangeC = ichangeC - 100;  
    } 
      
    printf("%d one dollar bills needed\n", gdollars); 
      
    printf("%d bills in total needed\n", DaDCount); 
      
    while(ichangeC % 25 != ichangeC) 
    { 
        quarters ++; 
        DaCount++; 
        ichangeC = ichangeC - 25; 
    } 
      
    printf("%d quarters needed\n", quarters); 
      
    while(ichangeC % 10 != ichangeC) 
    { 
        dimes++; 
        DaCount++; 
        ichangeC = ichangeC - 10; 
    } 
      
    printf("%d dimes needed\n", dimes); 
     
    while(ichangeC % 5 != ichangeC) 
    { 
        nickles++; 
        DaCount++; 
        ichangeC = ichangeC - 5; 
    } 
  
    printf("%d nickles needed\n", nickles); 
   
    while(ichangeC % 1 != ichangeC) 
    { 
        pennies++; 
        DaCount++; 
        ichangeC = ichangeC - 1; 
    } 
      
    printf("%d pennies needed\n", pennies); 
      
    printf("%d coins in total are needed!\n", DaCount); 
      
}

see the change

Advanced Greedy Algorithm for Change Machine

C