This is the first submit

input.txt

+7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450
\ No newline at end of file

submit.rb

+#Problem 1
+
+def problem1
+  result = 0
+  i = 0;
+
+  while (i < 1000) do
+    if (i % 3 == 0 || i % 5 == 0) then
+      result += i
+    end
+    i += 1
+  end
+
+  puts result
+
+end
+
+problem1
+
+#Problem 2
+
+def problem2 (nth)
+
+  number1 = 0
+  number2 = 1
+  result = 0
+
+  while (number2 < nth) do
+    if (number2.even?) then
+      result += number2
+    end
+    temp = number1 + number2
+    number1 = number2
+    number2 = temp
+  end
+  puts result
+end
+
+problem2(4_000_000)
+
+#Problem 3
+
+def probelm3 (arg)
+  nth = arg
+  x = 3
+  result = -1
+
+  while (Math.sqrt(x) < nth) do
+    res, rem = nth.divmod(x)
+    if (rem == 0) then
+      nth = nth / x
+      result = x
+      x += 2
+    else
+      x += 2
+    end
+
+  end
+
+  return result
+end
+
+puts probelm3 (600_851_475_143)
+
+#Problem 4
+
+def palindrome(arg)
+  temp = arg.to_s
+  return temp.reverse == temp
+end
+
+def problem4
+  result = 0
+  for x in 999.downto(100)
+    for y in 999.downto(100)
+      temp = x * y
+      if (palindrome (temp))then
+        if (temp > result) then
+          result = temp
+        end
+      end
+    end
+  end
+  return result
+end
+
+puts problem4
+
+#Problem 5
+
+def problem5
+  set = (1..20).to_a
+  return set.inject(:lcm)
+end
+
+puts problem5
+
+#Problem 6
+
+def problem6
+  sumOfSquares = 0
+  squareOfSum = 0
+  for x in 100.downto(0)
+    sumOfSquares += x * x
+    squareOfSum += x
+  end
+  squareOfSum = squareOfSum * squareOfSum
+  return squareOfSum - sumOfSquares
+end
+
+puts problem6
+
+#Problem 7
+
+def is_prime?(num)
+   Math.sqrt(num).floor.downto(2).each {|i| return false if num % i == 0}
+   return true
+end
+
+def problem7 (nth)
+  number = 0;
+  currentPrime = 2;
+  while (true) do
+    if (is_prime?(currentPrime)) then
+      number += 1
+      if (number == nth) then
+        return currentPrime
+      end
+    end
+    currentPrime += 1
+  end
+end
+
+puts problem7 (10_001)
+
+#Problem 8
+
+def problem8 (link)
+  File.open(link).each_line{ |s|
+    array_number = s.to_s.split('')
+    for i in 0..999
+      array_number[i] = array_number[i].to_i
+    end
+    result = 0
+    for i in 0..987
+      temp = array_number[i]
+      for x in 1..12
+        temp *= array_number[i + x]
+      end
+      if (temp > result) then
+        result = temp
+      end
+    end
+    return result
+  }
+end
+
+puts problem8('input.txt')
+
+#Problem 9
+
+def problem9
+  for a in 1..1000
+    for b in 1..1000
+      c = 1000 - a - b
+      if (Math.hypot(a, b) == c) then
+        return a * b * c;
+      end
+    end
+  end
+  return -1;
+end
+
+puts problem9
+
+# Problem 10
+
+# Cach thu 1: thoi gian tinh toan khoang 3'
+def is_prime?(num)
+   Math.sqrt(num).floor.downto(2).each {|i| return false if num % i == 0}
+   return true
+end
+
+def problem10 (nth)
+  result = 0
+  for i in 2..nth
+    if (is_prime?(i)) then
+      result += i
+    end
+  end
+  return result
+end
+
+puts problem10(2_000_000)
+
+# Cach thu 2: giam kich thuoc tinh toan, bang cach loai bo nhung so chan (even), thoi gian tinh toan giam xuong 1 nua, khoang gan 2' (Eliminating even numbers)
+def is_prime?(num)
+   Math.sqrt(num).floor.downto(2).each {|i| return false if num % i == 0}
+   return true
+end
+
+def problem10 (nth)
+  result = 0
+  for i in 2..nth
+    unless (i.even?) then
+      if (is_prime?(i)) then
+        result += i
+      end
+    end
+  end
+  return result
+end
+
+puts problem10(2_000_000)
+
+# Cach thu 3: toi uu nhat, thoi gian tinh toan khoang 1-2s @@ ap dung giai thuat Sieve of Eratosthenes
+def problem10 (nth)
+  sum = 0
+  array = Array.new(nth + 1) {true}
+  array[0] = false
+  array[1] = false
+  i = 2
+  while (i <= nth) do
+    if (array[i]) then
+
+      if (i*i < nth) then
+        array[i * i] = false;
+      end
+
+      factor = 1
+
+      while (i + factor * i < nth) do
+        array[i + i * factor] = false
+        factor += 1
+      end
+
+    end
+
+    i += 1
+  end
+
+  i = 0;
+  while (i <= nth) do
+    if array[i] then
+      sum += i
+    end
+    i += 1
+  end
+
+  return sum
+end
+
+puts problem10 (2_000_000)
+
+
+#problem 11