Add more solutions

Added solutions for problems 26, 27, 28, 29 and 30, both in C
and python

C/p026.c

@@ -0,0 +1,66 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <time.h>
+#include <gmp.h>
+
+int main(int argc, char **argv)
+{
+   int i, j, n, max = 0, max_n = 0;
+   double elapsed;
+   struct timespec start, end;
+   mpz_t k, div;
+
+   clock_gettime(CLOCK_MONOTONIC, &start);
+
+   mpz_init(k);
+   mpz_init(div);
+
+   for(i = 2; i < 1000; i++)
+   {
+      j = i;
+
+      while(j % 2 == 0 && j > 1)
+         j /= 2;
+
+      while(j % 5 == 0 && j > 1)
+         j /= 5;
+
+      mpz_set_ui(k, 9);
+
+      if(j == 1)
+         n = 0;
+      else
+      {
+         n = 1;
+
+         mpz_set_ui(div, j);
+
+         while(!mpz_divisible_p(k, div))
+         {
+            n++;
+            mpz_mul_ui(k, k, 10);
+            mpz_add_ui(k, k, 9);
+         }
+
+         if(n > max)
+         {
+            max = n;
+            max_n = i;
+         }
+      }
+   }
+
+   mpz_clears(k, div, NULL);
+
+   clock_gettime(CLOCK_MONOTONIC, &end);
+
+   elapsed=(end.tv_sec-start.tv_sec)+(double)(end.tv_nsec-start.tv_nsec)/1000000000;
+
+   printf("Project Euler, Problem 26\n");
+   printf("Answer: %d\n", max_n);
+
+   printf("Elapsed time: %.9lf seconds\n", elapsed);
+
+   return 0;
+}

C/p027.c

@@ -0,0 +1,56 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <time.h>
+#include "projecteuler.h"
+
+int main(int argc, char **argv)
+{
+   int a, b, n, p, count, max = 0, save_a, save_b;
+   double elapsed;
+   struct timespec start, end;
+
+   clock_gettime(CLOCK_MONOTONIC, &start);
+
+   for(a = -999; a < 1000; a++)
+   {
+      for(b = 2; b <= 1000; b++)
+      {
+         n = 0;
+         count = 0;
+
+         while(1)
+         {
+            p = n * n + a * n + b;
+
+            if(p > 1 && is_prime(p))
+            {
+               count++;
+               n++;
+            }
+            else
+            {
+               break;
+            }
+         }
+
+         if(count > max)
+         {
+            max = count;
+            save_a = a;
+            save_b = b;
+         }
+      }
+   }
+
+   clock_gettime(CLOCK_MONOTONIC, &end);
+
+   elapsed = (end.tv_sec - start.tv_sec) + (double)(end.tv_nsec - start.tv_nsec) / 1000000000;
+
+   printf("Project Euler, Problem 27\n");
+   printf("Answer: %d\n", save_a * save_b);
+
+   printf("Elapsed time: %.9lf seconds\n", elapsed);
+
+   return 0;
+}

C/p028.c

@@ -0,0 +1,36 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#define N 1001
+
+int main(int argc, char **argv)
+{
+   int i, j, step = 0, limit = N * N, sum = 1;
+   double elapsed;
+   struct timespec start, end;
+
+   clock_gettime(CLOCK_MONOTONIC, &start);
+
+   for(i = 0, j = 1; j < limit; i = (i + 1) % 4)
+   {
+      if(i == 0)
+      {
+         step += 2;
+      }
+
+      j += step;
+      sum += j;
+   }
+
+   clock_gettime(CLOCK_MONOTONIC, &end);
+
+   elapsed = (end.tv_sec - start.tv_sec) + (double)(end.tv_nsec - start.tv_nsec) / 1000000000;
+
+   printf("Project Euler, Problem 28\n");
+   printf("Answer: %d\n", sum);
+
+   printf("Elapsed time: %.9lf seconds\n", elapsed);
+
+   return 0;
+}

C/p029.c

@@ -0,0 +1,87 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <gmp.h>
+
+void selection_sort(mpz_t *v, int n);
+
+int main(int argc, char **argv)
+{
+   mpz_t a;
+   mpz_t powers[9801];
+   int i, j, count;
+   double elapsed;
+   struct timespec start, end;
+
+   clock_gettime(CLOCK_MONOTONIC, &start);
+
+   mpz_init(a);
+
+   for(i = 0; i < 9801; i++)
+   {
+      mpz_init(powers[i]);
+   }
+
+   for(i = 2; i <= 100; i++)
+   {
+      mpz_set_ui(a, i);
+      for(j = 2; j <= 100; j++)
+      {
+         mpz_pow_ui(powers[(i-2)*99+j-2], a, j);
+      }
+   }
+
+   mpz_clear(a);
+
+   selection_sort(powers, 9801);
+   count = 1;
+
+   for(i = 1; i < 9801; i++)
+   {
+      if(mpz_cmp(powers[i], powers[i-1]))
+      {
+         count++;
+      }
+   }
+
+   for(i = 0; i < 9801; i++)
+   {
+      mpz_clear(powers[i]);
+   }
+
+   clock_gettime(CLOCK_MONOTONIC, &end);
+
+   elapsed = (end.tv_sec - start.tv_sec) + (double)(end.tv_nsec - start.tv_nsec) / 1000000000;
+
+   printf("Project Euler, Problem 29\n");
+   printf("Answer: %d\n", count);
+
+   printf("Elapsed time: %.9lf seconds\n", elapsed);
+
+   return 0;
+}
+
+void selection_sort(mpz_t *v, int n)
+{
+   int i, j, min;
+   mpz_t tmp;
+
+   mpz_init(tmp);
+
+   for(i = 0; i < n - 1; i++)
+   {
+      min = i;
+      
+      for(j = i + 1; j < n; j++)
+      {
+         if(mpz_cmp(v[j], v[min])<0)
+         {
+            min = j;
+         }
+      }
+
+      mpz_set(tmp, v[min]);
+      mpz_set(v[min], v[i]);
+      mpz_set(v[i], tmp);
+   }
+}

C/p030.c

@@ -0,0 +1,42 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <time.h>
+
+int main(int argc, char **argv)
+{
+   int i, j, digit, sum, sum_tot = 0;
+   double elapsed;
+   struct timespec start, end;
+
+   clock_gettime(CLOCK_MONOTONIC, &start);
+
+   for(i = 10; i < 354295; i++)
+   {
+      j = i;
+      sum = 0;
+
+      while(j > 0)
+      {
+         digit = j % 10;
+         sum += (pow(digit, 5));
+         j /= 10;
+      }
+
+      if(sum == i)
+      {
+         sum_tot += i;
+      }
+   }
+
+   clock_gettime(CLOCK_MONOTONIC, &end);
+
+   elapsed=(end.tv_sec-start.tv_sec)+(double)(end.tv_nsec-start.tv_nsec)/1000000000;
+
+   printf("Project Euler, problem 30\n");
+   printf("Answer: %d\n", sum_tot);
+
+   printf("Elapsed time: %.9lf seconds\n", elapsed);
+
+   return 0;
+}

Python/p026.py

@@ -0,0 +1,43 @@
+#!/usr/bin/python3
+
+from timeit import default_timer
+
+def main():
+    start = default_timer()
+
+    max_ = 0
+
+    for i in range(2, 1000):
+        j = i
+
+        while j % 2 == 0 and j > 1:
+            j = j // 2
+
+        while j % 5 == 0 and j > 1:
+            j = j // 5
+
+        k = 9
+
+        if j == 1:
+            n = 0
+        else:
+            n = 1
+            div = j
+            while k % div != 0:
+                n = n + 1
+                k = k * 10
+                k = k + 9
+
+            if n > max_:
+                max_ = n
+                max_n = i
+
+    end = default_timer()
+
+    print('Project Euler, Problem 26')
+    print('Answer: {}'.format(max_n))
+
+    print('Elapsed time: {:.9f} seconds'.format(end - start))
+
+if __name__ == '__main__':
+    main()

Python/p027.py

@@ -0,0 +1,38 @@
+#!/usr/bin/python3
+
+from timeit import default_timer
+from projecteuler import is_prime
+
+def main():
+    start = default_timer()
+
+    max_ = 0
+
+    for a in range(-999, 1000):
+        for b in range(2, 1001):
+            n = 0
+            count = 0
+
+            while True:
+                p = n * n + a * n + b
+
+                if p > 1 and is_prime(p):
+                    count = count + 1
+                    n = n + 1
+                else:
+                    break
+
+            if count > max_:
+                max_ = count
+                save_a = a
+                save_b = b
+
+    end = default_timer()
+
+    print('Project Euler, Problem 27')
+    print('Answer: {}'.format(save_a * save_b))
+
+    print('Elapsed time: {:.9f} seconds'.format(end - start))
+
+if __name__ == '__main__':
+    main()

Python/p028.py

@@ -0,0 +1,30 @@
+#!/usr/bin/python3
+
+from timeit import default_timer
+
+def main():
+    start = default_timer()
+
+    limit = 1001 * 1001
+
+    i = 0
+    j = 1
+    step = 0
+    sum_ = 1
+
+    while j < limit:
+        if i == 0:
+            step = step + 2
+        j = j + step
+        sum_ = sum_ + j
+        i = (i + 1) % 4
+
+    end = default_timer()
+
+    print('Project Euler, Problem 28')
+    print('Answer: {}'.format(sum_))
+
+    print('Elapsed time: {:.9f} seconds'.format(end - start))
+
+if __name__ == '__main__':
+    main()

Python/p029.py

@@ -0,0 +1,34 @@
+#!/usr/bin/python3
+
+from numpy import zeros
+
+from timeit import default_timer
+
+def main():
+    start = default_timer()
+
+    powers = zeros(9801)
+
+    for i in range(2, 101):
+        a = i
+        for j in range(2, 101):
+            powers[(i-2)*99+j-2] = a ** j
+
+    powers = list(powers)
+    powers.sort()
+    
+    count = 1
+
+    for i in range(1, 9801):
+        if powers[i] != powers[i-1]:
+            count = count + 1
+
+    end = default_timer()
+
+    print('Project Euler, Problem 29')
+    print('Answer: {}'.format(count))
+
+    print('Elapsed time: {:.9f} seconds'.format(end - start))
+
+if __name__ == '__main__':
+    main()

Python/p030.py

@@ -0,0 +1,32 @@
+#!/usr/bin/python3
+
+from numpy import zeros
+
+from timeit import default_timer
+
+def main():
+    start = default_timer()
+
+    tot = 0
+
+    for i in range(10, 354295):
+        j = i
+        sum_ = 0
+
+        while j > 0:
+            digit = j % 10
+            sum_ = sum_ + digit ** 5
+            j = j // 10
+
+        if sum_ == i:
+            tot = tot + i
+
+    end = default_timer()
+
+    print('Project Euler, Problem 30')
+    print('Answer: {}'.format(tot))
+
+    print('Elapsed time: {:.9f} seconds'.format(end - start))
+
+if __name__ == '__main__':
+    main()