Atcoder beginner selections

abs/ABC049C.rb

@@ -0,0 +1,24 @@
+s = gets.chomp
+
+exit if s.length > 10 ** 5
+
+while s.length > 0
+  if s.index("eraser") == 0
+    s.slice!(0, 6)
+  elsif s.index("erase") == 0
+    s.slice!(0, 5)
+  elsif s.index("dreameraser") == 0
+    s.slice!(0, 11)
+  elsif s.index("dreamerase") == 0
+    s.slice!(0, 10)
+  elsif s.index("dreamer") == 0
+    s.slice!(0, 7)
+  elsif s.index("dream") == 0
+    s.slice!(0, 5)
+  else
+    break
+  end
+end
+
+result = s.length == 0 ? "YES" : "NO"
+puts result

abs/ABC081A.rb

@@ -0,0 +1,8 @@
+input = gets.to_i(2)
+result = 0
+
+(0..2).each do |num|
+  result += input[num]
+end
+
+print "#{result}\n"

abs/ABC081B.rb

@@ -0,0 +1,22 @@
+n = gets.to_i
+given = gets.chomp.split(' ').map(&:to_i)
+
+counter = 0
+condition_violated = false
+
+while true do
+  n.times do |num|
+    if given[num] % 2 == 0
+      given[num] = given[num] / 2
+    else
+      condition_violated = true
+      break
+    end
+  end
+  if condition_violated
+    break
+  end
+  counter += 1
+end
+
+puts counter

abs/ABC083B.rb

@@ -0,0 +1,26 @@
+input = gets.chomp.split(' ').map(&:to_i)
+
+N = input[0]
+A = input[1]
+B = input[2]
+
+BASE = 10
+
+exit unless A && B && N
+exit if BASE ** 4 < N || A < 1|| B  < A || 36 < B
+
+applied_sum = 0
+
+(1..N).each do |num|
+  num_digit = Math.log10(num).to_i
+  sum = 0
+  remain = num
+  num_digit.downto(0) do |digit|
+    target_digit_num = remain / (BASE ** digit)
+    remain -= target_digit_num * (BASE ** digit)
+    sum += target_digit_num
+  end
+  applied_sum += num if A <= sum && sum <= B
+end
+
+puts applied_sum

abs/ABC085B.rb

@@ -0,0 +1,14 @@
+N = gets.to_i
+input = []
+
+N.times do |num|
+  input << gets.to_i
+end
+
+tower = []
+
+input.each do |num|
+  tower << num if tower.select { |val| val == num }.count == 0
+end
+
+puts tower.length

abs/ABC085C.rb

@@ -0,0 +1,16 @@
+N, Y = gets.chomp.split(' ').map(&:to_i)
+
+max_10000yen_count = Y / 10000
+
+(0..max_10000yen_count).each do |num_1|
+  remain = N - num_1
+  (0..remain).each do |num_2|
+    num_3 = N - num_1 - num_2
+    if Y - (num_1 * 10000 + num_2 * 5000 + num_3 * 1000) == 0
+      puts "#{num_1} #{num_2} #{num_3}"
+      exit
+    end
+  end
+end
+
+puts "-1 -1 -1"

abs/ABC086C.rb

@@ -0,0 +1,50 @@
+class Point
+  def initialize(x, y)
+    @x = x
+    @y = y
+  end
+
+  def length_to(x, y)
+    (@x - x).abs + (@y - y).abs
+  end
+
+  def update(x, y)
+    @x = x
+    @y = y
+  end
+end
+
+N = gets.chomp.to_i
+exit if N > 10 ** 5
+
+itinerary = []
+N.times do |num|
+  t, x, y = gets.chomp.split(' ').map(&:to_i)
+  itinerary << [t, x, y]
+end
+
+current_position = Point.new(0, 0)
+current_time = 0
+goal = true
+
+itinerary.each do |destination|
+  t, x, y = destination
+  length = current_position.length_to(x, y)
+  remain_time = t - current_time
+
+  if length > remain_time
+    goal = false
+    break
+  end
+
+  if (length.odd? && remain_time.even?) || (length.even? && remain_time.odd?)
+    goal = false
+    break
+  end
+
+  current_position.update(x, y)
+  current_time = t
+end
+
+answer = goal ? "Yes" : "No"
+puts answer

abs/ABC087B.rb

@@ -0,0 +1,40 @@
+A = gets.to_i
+B = gets.to_i
+C = gets.to_i
+X = gets.to_i
+
+A_PRICE = 500
+B_PRICE = 100
+C_PRICE = 50
+
+counter = 0
+
+a_arr = []
+b_arr = []
+c_arr = []
+
+(0..A).each do |num|
+  a_arr << A_PRICE * num
+end
+
+(0..B).each do |num|
+  b_arr << B_PRICE * num
+end
+
+(0..C).each do |num|
+  c_arr << C_PRICE * num
+end
+
+(0..A).each do |num_a|
+  a_price = A_PRICE * num_a
+  (0..B).each do |num_b|
+    b_price = B_PRICE * num_b
+    (0..C).each do |num_c|
+      c_price = C_PRICE * num_c
+      sum = a_price + b_price + c_price
+       counter += 1 if sum == X
+    end
+  end
+end
+
+puts counter

abs/ABC088B.rb

@@ -0,0 +1,22 @@
+N = gets.to_i
+arr = gets.chomp.split(' ').map(&:to_i)
+
+exit unless 1 <= N && N <= 100
+arr.each do |num|
+  exit unless 1 <= num && num <= 100
+end
+
+alice_result = 0
+bob_result = 0
+
+counter = 0
+arr.sort.reverse.each do |num|
+  if counter.even?
+    alice_result += num
+  else
+    bob_result += num
+  end
+  counter += 1
+end
+
+puts alice_result - bob_result