80 lines
1.8 KiB
C
80 lines
1.8 KiB
C
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <time.h>
|
|
|
|
int main(int argc, char **argv)
|
|
{
|
|
int i, value, n;
|
|
int digits[1000005];
|
|
double elapsed;
|
|
struct timespec start, end;
|
|
|
|
clock_gettime(CLOCK_MONOTONIC, &start);
|
|
|
|
i = 1;
|
|
value = 1;
|
|
|
|
while(i <= 1000000)
|
|
{
|
|
if(value < 10)
|
|
{
|
|
digits[i-1] = value;
|
|
i++;
|
|
}
|
|
else if(value < 100)
|
|
{
|
|
digits[i-1] = value / 10;
|
|
digits[i] = value % 10;
|
|
i += 2;
|
|
}
|
|
else if(value < 1000)
|
|
{
|
|
digits[i-1] = value / 100;
|
|
digits[i] = (value / 10) % 10;
|
|
digits[i+1] = value % 10;
|
|
i += 3;
|
|
}
|
|
else if(value < 10000)
|
|
{
|
|
digits[i-1] = value / 1000;
|
|
digits[i] = (value / 100) % 10;
|
|
digits[i+1] = (value / 10) % 10;
|
|
digits[i+2] = value % 10;
|
|
i += 4;
|
|
}
|
|
else if(value < 100000)
|
|
{
|
|
digits[i-1] = value / 10000;
|
|
digits[i] = (value / 1000) % 10;
|
|
digits[i+1] = (value / 100) % 10;
|
|
digits[i+2] = (value / 10) % 10;
|
|
digits[i+3] = value % 10;
|
|
i += 5;
|
|
}
|
|
else if(value < 1000000)
|
|
{
|
|
digits[i-1] = value / 100000;
|
|
digits[i] = (value / 10000) % 10;
|
|
digits[i+1] = (value / 1000) % 10;
|
|
digits[i+2] = (value / 100) % 10;
|
|
digits[i+3] = (value / 10) % 10;
|
|
digits[i+4] = value % 10;
|
|
i += 6;
|
|
}
|
|
value++;
|
|
}
|
|
|
|
n = digits[0] * digits[9] * digits[99] * digits[999] * digits[9999] * digits[99999] * digits[999999];
|
|
|
|
clock_gettime(CLOCK_MONOTONIC, &end);
|
|
|
|
elapsed = (end.tv_sec - start.tv_sec) + (double)(end.tv_nsec - start.tv_nsec) / 1000000000;
|
|
|
|
printf("Project Euler, Problem 40\n");
|
|
printf("Answer: %d\n", n);
|
|
|
|
printf("Elapsed time: %.9lf seconds\n", elapsed);
|
|
|
|
return 0;
|
|
}
|