Merge pull request TheAlgorithms#266 from daniel-s-ingram/master

Brute force solution to Problem 10

Author: harshildarji

Project Euler/Problem 10/sol1.py

@@ -0,0 +1,33 @@
+from __future__ import print_function
+from math import sqrt
+
+def is_prime(n):
+	for i in xrange(2, int(sqrt(n))+1):
+		if n%i == 0:
+			return False
+
+	return True
+
+def sum_of_primes(n):
+	if n > 2:
+		sumOfPrimes = 2
+	else:
+		return 0
+
+	for i in xrange(3, n, 2):
+		if is_prime(i):
+			sumOfPrimes += i
+
+	return sumOfPrimes
+
+if __name__ == '__main__':
+	import sys
+
+	if len(sys.argv) == 1:
+		print(sum_of_primes(2000000))
+	else:
+		try:
+			n = int(sys.argv[1])
+			print(sum_of_primes(n))
+		except ValueError:
+			print('Invalid entry - please enter a number.')

Project Euler/Problem 15/sol1.py

@@ -0,0 +1,20 @@
+from __future__ import print_function
+from math import factorial, ceil
+
+def lattice_paths(n):
+	n = 2*n #middle entry of odd rows starting at row 3 is the solution for n = 1, 2, 3,...
+	k = n/2
+
+	return factorial(n)/(factorial(k)*factorial(n-k))
+
+if __name__ == '__main__':
+	import sys
+
+	if len(sys.argv) == 1:
+		print(lattice_paths(20))
+	else:
+		try:
+			n = int(sys.argv[1])
+			print(lattice_paths(n))
+		except ValueError:
+			print('Invalid entry - please enter a number.')

Project Euler/Problem 25/sol1.py

@@ -0,0 +1,26 @@
+from __future__ import print_function
+
+def fibonacci(n):
+	if n == 1 or type(n) is not int:
+		return 0
+	elif n == 2:
+		return 1
+	else:
+		sequence = [0, 1]
+		for i in xrange(2, n+1):
+			sequence.append(sequence[i-1] + sequence[i-2])
+
+		return sequence[n]
+
+def fibonacci_digits_index(n):
+	digits = 0
+	index = 2
+
+	while digits < n:
+		index += 1
+		digits = len(str(fibonacci(index)))
+
+	return index
+
+if __name__ == '__main__':
+	print(fibonacci_digits_index(1000))

Project Euler/Problem 28/sol1.py

@@ -0,0 +1,24 @@
+from __future__ import print_function
+from math import ceil
+
+def diagonal_sum(n):
+	total = 1
+
+	for i in xrange(1, int(ceil(n/2.0))):
+		odd = 2*i+1
+		even = 2*i
+		total = total + 4*odd**2 - 6*even
+
+	return total
+
+if __name__ == '__main__':
+	import sys
+
+	if len(sys.argv) == 1:
+		print(diagonal_sum(1001))
+	else:
+		try:
+			n = int(sys.argv[1])
+			diagonal_sum(n)
+		except ValueError:
+			print('Invalid entry - please enter a number')