85 lines
2.7 KiB
C
85 lines
2.7 KiB
C
/* 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?
|
|
*
|
|
* 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.*/
|
|
|
|
#define _POSIX_C_SOURCE 199309L
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <time.h>
|
|
|
|
int main(int argc, char **argv)
|
|
{
|
|
/* Number of letters for numbers from 1 to 19.*/
|
|
int n1_19[19] = {3, 3, 5, 4, 4, 3, 5, 5, 4, 3, 6, 6, 8, 8, 7, 7, 9, 8, 8};
|
|
/* Number of letters for "twenty", "thirty", ..., "ninety".*/
|
|
int n20_90[8] = {6, 6, 5, 5, 5, 7, 6, 6};
|
|
/* Number of letters for "one hundred and", "two hundred and", ...,
|
|
* "nine hundred and".*/
|
|
int n100_900[9] = {13, 13, 15, 14, 14, 13, 15, 15, 14};
|
|
/* Number of letters for 1000.*/
|
|
int n1000 = 11;
|
|
int sum = 0, i, j;
|
|
double elapsed;
|
|
struct timespec start, end;
|
|
|
|
clock_gettime(CLOCK_MONOTONIC, &start);
|
|
|
|
/* Sum the letters of the first 19 numbers.*/
|
|
for(i = 0; i < 19; i++)
|
|
{
|
|
sum += n1_19[i];
|
|
}
|
|
|
|
/* Add the letters of the numbers from 20 to 99.*/
|
|
for(i = 0; i < 8; i++)
|
|
{
|
|
/* "Twenty", "thirty", ... "ninety" are used ten times each
|
|
* (e.g. "twenty", "twenty one", "twenty two", ..., "twenty nine").*/
|
|
n20_90[i] *= 10;
|
|
/* Add "one", "two", ..., "nine".*/
|
|
for(j = 0; j < 9; j++)
|
|
{
|
|
n20_90[i] += n1_19[j];
|
|
}
|
|
sum += n20_90[i];
|
|
}
|
|
|
|
/* Add the letters of the numbers from 100 to 999.*/
|
|
for(i = 0; i < 9; i++)
|
|
{
|
|
/* "One hundred and", "two hundred and",... are used 100 times each.*/
|
|
n100_900[i] *= 100;
|
|
/* Add "one" to "nineteen".*/
|
|
for(j = 0; j < 19; j++)
|
|
{
|
|
n100_900[i] += n1_19[j];
|
|
}
|
|
/* Add "twenty" to "ninety nine", previously calculated.*/
|
|
for(j = 0; j < 8; j++)
|
|
{
|
|
n100_900[i] += n20_90[j];
|
|
}
|
|
/* "One hundred", "two hundred", ... don't have the "and", so remove
|
|
* three letters for each of them.*/
|
|
sum += n100_900[i] - 3;
|
|
}
|
|
|
|
/* Add "one thousand".*/
|
|
sum += n1000;
|
|
|
|
clock_gettime(CLOCK_MONOTONIC, &end);
|
|
|
|
elapsed = (end.tv_sec - start.tv_sec) + (double)(end.tv_nsec - start.tv_nsec) / 1000000000;
|
|
|
|
printf("Project Euler, Problem 17\n");
|
|
printf("Answer: %d\n", sum);
|
|
|
|
printf("Elapsed time: %.9lf seconds\n", elapsed);
|
|
|
|
return 0;
|
|
}
|