C Programming Language(week1, problem set)

https://cs50.harvard.edu/college/psets/1/

1. Hello

#include <stdio.h>
#include <cs50.h>
 
int main(void)
{
    string name = get_string("What is your name?\n");
    printf("hello, %s\n", name);
}

2a. Mario less

#include <cs50.h>
#include <stdio.h>
 
int main(void)
{
    int stairs = get_int("Height: ");
    while(!(stairs >= 1 && stairs <= 8)) stairs = get_int("Height: ");
    for(int i = 0; i < stairs; i++){
        for(int j = stairs; j > i + 1; j--){
            printf(" ");
        }
        
        for(int j = 0; j <= i; j++){
            printf("#");
        }
        printf("\n");
    }
}

2b. Mario more

#include <cs50.h>
#include <stdio.h>
 
int main(void)
{
    int stairs = get_int("Height: ");
    while(!(stairs >= 1 && stairs <= 8)) stairs = get_int("Height: ");
    
    for(int i = 0; i < stairs; i++){
        for(int j = stairs; j > i + 1; j--){
            printf(" ");
        }
        
        for(int j = 0; j < i + 1; j++){
            printf("#");
        }
        
        printf("  ");
        
        for(int j = 0; j < i + 1; j++){
            printf("#");
        }
        
        /*for(int j = stairs; j > i + 1; j--){
            printf(" ");
        }*/
        
        printf("\n");
    }
}

3a. Cash

#include <stdio.h>
#include <math.h>
#include <cs50.h>
 
int main(void){
    float change = get_float("Change owed: ");
    while(!(change >= 0.00)) change = get_float("Change owed: ");
    
    int coins = round(change * 100);
    
    int count = 0;
    while(coins != 0){
        if(coins >= 25){
            int temp = coins/25;
            coins = coins - (temp * 25);
            count += temp;
        }
        if(coins >= 10){
            int temp = coins/10;
            coins = coins - (temp * 10);
            count += temp;
        }
        if(coins >= 5){
            int temp = coins/5;
            coins = coins - (temp * 5);
            count += temp;
        }
        count += coins;
        coins = 0;
    }
    
    printf("%i\n", count);
}
 

3b. Credit

#include <cs50.h>
#include <stdio.h>
 
int main(void){
    long number = get_long("Number: ");
    char *answer = NULL;
    
    if((number/1000000000000 > 1 && (number/1000000000000) % 10 == 4) ||
      (number/1000000000000000 > 1 && (number/1000000000000000) % 10 == 4)) {
        
        answer = malloc(5 * sizeof(char));
        answer = "VISA";
    }
    else if((number/100000000000000) > 1 && 
            ((number/10000000000000) % 100 == 34 || (number/10000000000000) % 100 == 37)){
       
        answer = malloc(5 * sizeof(char));
        answer = "AMEX";
    } 
    else if((number/100000000000000) > 1 && 
            ((number/100000000000000) % 100 >= 51 && (number/100000000000000) % 100 <= 55)) {
        
        answer = malloc(10 * sizeof(char));
        answer = "MASTERCARD";
        printf("master?\n");
    } else {
        printf("INVALID\n");
        return 0;
    }
    
    int forSum = 0;
    for(long i = 10; i <= number; i *= 100){
        int divNum = ((number % (i * 10))/i) * 2;
        if(divNum >= 10){
            int temp = divNum % 10;
            divNum /= 10;
            forSum += temp + divNum;
        } else {
            forSum += divNum;
        }
        //printf("%i, %ld forSum, %i\n", forSum, i, divNum);
    }
    
    int restSum = 0;
    for(long i = 10; i <= number * 10; i *= 100){
        int restNum = (number % (i))/(i/10);
        restSum += restNum;
        //printf("%i, %ld restSum, %i\n", restSum, i, restNum);
    }
    if((forSum + restSum) % 10 == 0){
        printf("%s\n", answer);
    } else {
        printf("INVALID\n");
    }
    
}