DevPreWork01-LAT

problem03.rb

@@ -0,0 +1,20 @@
+#The prime factors of 13195 are 5,7,13 and 29
+#what is the largest prime factor of the number 600851475143
+
+def prime? n
+    (2..(n-1)).each { |x| return false if n % x == 0 }
+    true
+end
+
+n = 600851475143
+a = []
+product_sum = 1
+x = 2 
+
+while product_sum < n
+    if n % x == 0 && prime?(x)
+        a << x
+        product_sum *= x
+    end
+    x += 1
+end

problem05.rb

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+#2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.
+
+#What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20?
+
+class Numeric
+    def divisible_to?(x)
+        self > 0 and x.downto(1).all? { |i| self % i == 0 }
+    end
+end
+
+def divisible_to(x)
+    if x < 1
+        return false
+        elsif x == 1
+        return 1
+        else
+        n = 0
+        step = divisible_to(x-1)
+        until n.divisible_to? x
+            n += step
+        end
+
+        return n
+    end
+
+end
+
+puts divisible_to(20)

problem08.rb

@@ -0,0 +1,41 @@
+# n = 7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450
+#Find the greatest product of five consecutive digits in the 1000-digit number.
+n = <<EOS
+73167176531330624919225119674426574742355349194934
+96983520312774506326239578318016984801869478851843
+85861560789112949495459501737958331952853208805511
+12540698747158523863050715693290963295227443043557
+66896648950445244523161731856403098711121722383113
+62229893423380308135336276614282806444486645238749
+30358907296290491560440772390713810515859307960866
+70172427121883998797908792274921901699720888093776
+65727333001053367881220235421809751254540594752243
+52584907711670556013604839586446706324415722155397
+53697817977846174064955149290862569321978468622482
+83972241375657056057490261407972968652414535100474
+82166370484403199890008895243450658541227588666881
+16427171479924442928230863465674813919123162824586
+17866458359124566529476545682848912883142607690042
+24219022671055626321111109370544217506941658960408
+07198403850962455444362981230987879927244284909188
+84580156166097919133875499200524063689912560717606
+05886116467109405077541002256983155200055935729725
+71636269561882670428252483600823257530420752963450
+EOS
+
+consec = 5
+
+def product integer
+    prod = 1
+    integer.to_s.length.times { |i| prod *= integer.to_s[i].to_i }
+    prod
+end
+
+array_results = []
+(0..n.to_s.length - consec).each do |counter|
+    select  = n.to_s[counter..counter + consec - 1]
+    prod    = product select
+    array_results << prod
+end
+
+puts "The max product of five consecutive digits in the integer n is #{array_results.max}."