Euler Project - Number Letter Counts

[jwroblewski44]

Hello!
I am working on Euler Project exercise number 17. Here is the problem from the website.

"If the numbers 1 to 5 are written out in words: one, two, three, four, five, then there are 3 + 3 + 5 + 4 + 4 = 19 letters used in total.If all the numbers from 1 to 1000 (one thousand) inclusive were written out in words, how many letters would be used?"

Here is my code:

#include <stdio.h>
#include <string.h>


#define LENGTHOFHUNDRED         7
#define LENGTHOFONETHOUSAND     11
#define NUMSTART                1
#define NUMEND                  1000
#define ANDLENGTH               3


static char * base_digits[] = { "one" , "two" , "three" , "four" , "five" , "six" , "seven" , "eight" , "nine" };
static char * teens[] = { "eleven" , "twelve" , "thirteen" , "fourteen" , "fifteen" , "sixteen" , "seventeen" , "eighteen" , "nineteen" };
static char * mults_of_ten[] = { "ten" , "twenty" , "thirty" , "forty" , "fifty" , "sixty" , "seventy" , "eighty" , "ninety" };


unsigned int count_letters( unsigned int );


int main(){
        unsigned int count = 0 , i;


        for( i = NUMSTART; i <= NUMEND; i++ )
                count += count_letters( i );
        printf( "total letters-> %d\n" , count );
        return 0;
}
unsigned int count_letters( unsigned int num ){
        if( num < 20 && num > 10 )
                return strlen( teens[ num - 11 ] );
        if( num == 1000 )
                return LENGTHOFONETHOUSAND;


        unsigned int digitcount = 0 , n , mdivisor = 1;


        if( num > 100 && ( num % 100 ) )
                digitcount += ANDLENGTH;
        do{
                num -= ( n = num % ( mdivisor *= 10 ) );
                if( n ){
                        if( n < 10 )
                                digitcount += strlen( base_digits[ n - 1 ] );
                        else if( n < 100 )
                                digitcount += strlen( mults_of_ten[ ( n / 10 - 1 ) ] );
                        else
                                digitcount += strlen( base_digits[ ( n / 100 - 1 ) ] ) + LENGTHOFHUNDRED;
                }
        }while( num );
        return digitcount;
}

Can someone show me where my logic went awry?

[Salem]

So through your tests, which number does it first fail on?

Or even which number(s) in general fail.

[dmh2000]

why not print the actual strings besides the letter count to see what the code is really generating.

[Matticus]

What exactly is it doing that you don't expect?

And are you sure you're supposed to include the word "and" in the letter count? You should be able to count to 1000 without using "and".

[jwroblewski44]

Sorry, this was at the end of the problem.

NOTE: Do not count spaces or hyphens. For example, 342 (three hundred and forty-two) contains 23 letters and 115 (one hundred and fifteen) contains 20 letters. The use of "and" when writing out numbers is in compliance with British usage.

When I run in on the numbers 1 through 5 I get what is expected, 19. And when I run it on just the number 342, I get 23. And 20 for the number 115.

But when I try to execute it with the final parameters, starting at 1 and ending at 1000, I get "total letters-> 21088". Which is not the correct answer.

[phantomotap]

O_o

The reason for, and joy of, Project Euler is finding solutions so I'm hesitant to give you any specific advice.

So, I'm pretty much stuck just reiterating what Salem and dmh2000 has said: use some standard debugging methods to find where you first go wrong and with that in mind you can find the flaw in your implementation.

Soma

[jwroblewski44]

Enough said. Thanks for all the advice. And you're right, it will be much sweeter knowing I got to the center of the lollipop by myself.

[Adak]

why not print the actual strings besides the letter count to see what the code is really generating.

Perfect.

[jamesedmonds]

Not the answer they are looking for by the example given but by the question of how many letters are used, I'd have to say 18.