Project Euler and Ruby Judo solutions

combination.rb

@@ -0,0 +1,10 @@
+def combinations(first_array, second_array)
+	new_array = [ ]
+	first_array.each do |x| 
+		second_array.each do |y| 
+			new_array.push(x + y)
+		end
+	end
+	puts new_array 
+end
+combinations(["on","in"],["to","rope"])

count.rb

@@ -0,0 +1,26 @@
+	PLAYERS = 10
+	END_COUNT = 100
+
+def count
+	direction = 1
+	person = 1
+	count = 1
+	until count > END_COUNT do
+		puts "Person #{person} says #{count}."
+		count +=1
+		if count % 7 == 0
+			direction *= -1
+		end
+		if count % 11 == 0
+			person += direction
+		end
+		person += direction
+		if person < 1
+			person += PLAYERS
+		end
+		if person > PLAYERS
+			person -= PLAYERS
+		end
+	end
+end
+count

countAdv.rb

@@ -0,0 +1,23 @@
+def count (players, end_count)
+	direction = 1
+	person = 1
+	count = 1
+	until count > end_count do
+		puts "Person #{person} says #{count}."
+		count +=1
+		if count % 7 == 0
+			direction *= -1
+		end
+		if count % 11 == 0
+			person += direction
+		end
+		person += direction
+		if person < 1
+			person += players
+		end
+		if person > players
+			person -= players
+		end
+	end
+end
+count(10, 100)

evenFib.rb

@@ -0,0 +1,15 @@
+def fib(n)
+	x=1
+	y=2
+	sum=2
+	until y > n do
+		z= x+y
+		if z%2 == 0
+			sum = sum + z
+		end
+		x=y
+		y=z
+	end
+	puts sum
+end
+fib(4000000)

factorial.rb

@@ -0,0 +1,9 @@
+def factorial(x)
+	y=1
+	while x > 1 do
+		y = x*(x-1) * y
+		x-=2
+	end
+	puts y
+end
+factorial(5)

isPrime.rb

@@ -0,0 +1,23 @@
+def is_prime(n)
+    if n < 2
+        return false
+    end
+    if n == 2
+        return true
+    end
+    if n % 2 == 0
+    	return false
+    end
+    i = 3
+    while i < n**0.5 + 1
+        if n % i == 0
+        	return false
+        end 
+        i += 2
+    end
+    return true
+end
+
+is_prime(7)
+
+is_prime(14)

multiples.rb

@@ -0,0 +1,9 @@
+sum = 0
+for x in (1...1000)
+	if x%3 == 0
+		sum = sum+x
+	elsif x%5 == 0
+		sum = sum + x
+	end
+	puts sum
+end

overlap.rb

@@ -0,0 +1,40 @@
+
+	BOTTOMLEFT = 0
+	TOPRIGHT = 1
+	X = 0
+	Y = 1
+
+def overlap(a,b)
+	case true
+		when (a[BOTTOMLEFT][X] <= b[BOTTOMLEFT][X]) && (a[BOTTOMLEFT][Y] <= b[BOTTOMLEFT][Y])
+			if (a[TOPRIGHT][X] > b[BOTTOMLEFT][X]) && (a[TOPRIGHT][Y] > b[BOTTOMLEFT][Y])
+				puts true
+			else
+				puts false
+			end
+		when (a[BOTTOMLEFT][X] <= b[BOTTOMLEFT][X]) && (a[BOTTOMLEFT][Y] > b[BOTTOMLEFT][Y])
+			if (a[TOPRIGHT][X] > b[BOTTOMLEFT][X]) && (b[TOPRIGHT][Y] > a[BOTTOMLEFT][Y])
+				puts true
+			else
+				puts false
+			end
+		when (a[BOTTOMLEFT][X] > b[BOTTOMLEFT][X]) && (a[BOTTOMLEFT][Y] > b[BOTTOMLEFT][Y])
+			if (b[BOTTOMLEFT][X] > a[BOTTOMLEFT][X]) && (b[TOPRIGHT][Y] > a[BOTTOMLEFT][Y])
+				puts true
+			else
+				puts false
+			end
+		when (a[BOTTOMLEFT][X] > b[BOTTOMLEFT][X]) && (a[BOTTOMLEFT][Y] <= b[BOTTOMLEFT][Y])
+			if (b[BOTTOMLEFT][X] > a[TOPRIGHT][X]) && (a[TOPRIGHT][Y] > b[BOTTOMLEFT][Y])
+				puts true
+			else
+				puts false
+			end
+		else 
+			puts false
+		end
+
+end
+
+overlap([[0,0],[3,3]],[[1,1],[4,5]])
+overlap([[0,0],[1,4]],[[1,1],[3,2]])

pal.rb

@@ -0,0 +1,26 @@
+def largest_palindrome(number_of_digits)
+	starting_value = (10 ** number_of_digits) -1
+	biggest_palindrome = 0
+	i = starting_value
+	j = starting_value
+	until i == 0 do
+		until j == 0 do
+			value = i * j
+			if is_palindrome(value)
+				if value > biggest_palindrome
+					biggest_palindrome = value
+				end
+			end
+			j -= 1
+		end
+		i -=1
+		j= starting_value
+	end
+	puts biggest_palindrome
+end
+
+def is_palindrome(value)
+	return value.to_s == value.to_s.reverse
+end
+
+largest_palindrome(3)

power.rb

@@ -0,0 +1,8 @@
+def power(x,y)
+	z=x*x
+	(y-2).times do
+		z=z*x
+	end
+	puts z
+end
+power(3,4)

prime.rb

@@ -0,0 +1,27 @@
+def largest_prime_factor(input)
+	divisor = 1
+	while true
+		if input % divisor == 0
+			factor = input/divisor
+			if is_prime(factor)
+				puts factor
+				return 
+			end
+		end
+		divisor +=1
+	end
+end
+
+def is_prime(value)
+	if value%2==0
+		return false
+	end
+	(3..(value/2)).step(2) do |i|
+		if value%i==0
+			return false
+		end
+	end
+	return true
+end
+
+largest_prime_factor(600851475143)

unique.rb

@@ -0,0 +1,17 @@
+def uniques(input_array)
+	new_array = [ ]
+	input_array.each do |x| 
+		exists = false
+		new_array.each do |y| 
+				if (x == y)
+					exists = true
+				end
+		end
+		if !exists 
+			new_array.push(x)
+		end
+	end
+	puts new_array
+end
+
+uniques([1,5,"frog",2,1,3,"frog"])

uniques.rb

@@ -0,0 +1,17 @@
+def uniques(input)
+	new = [input[0]]
+	i = (input.length) -1
+	j = (new.length) -1
+	until i == -1
+		until j == -1
+			if input[i] != new[j]
+			new.push(input[i])
+			end
+		end
+		j -=1
+	end
+	i -=1
+	puts new
+end
+
+uniques([1,5,"frog", 2,1,3, "frog"])