AOJ（問題集）3

AIZU ONLINE JUDGE: Programming Challenge
　

0021 Parallelism

$<.readlines.drop(1).map {|a| a.split.map(&:to_r)}.each do |x1, y1, x2, y2, x3, y3, x4, y4|
  puts((x2 - x1) * (y4 - y3) == (x4 - x3) * (y2 - y1) ? "YES" : "NO")
end

単純な問題なのに、自分の解き方ではどうしてもダメだったので、他の人のを参考に。to_f じゃなくて to_r がミソなのかなあ。
　

0022 Maximum Sum Sequence

while (n = $<.gets.to_i).nonzero?
  given = (1..n).map {$<.gets.to_i}
  max = -Float::INFINITY
  n.times do |i|
    sum = 0
    (i...n).each do |j|
      sum += given[j]
      max = sum if sum > max
    end
  end
  puts max
end

0023 Circles Intersection

$<.readlines.drop(1).map {|a| a.split.map(&:to_f)}.each do |xa, ya, ra, xb, yb, rb|
  l = Math.sqrt((xb - xa) ** 2 + (yb - ya) ** 2)
  r = ra - rb
  puts case
       when l < r  then 2
       when l < -r then -2
       when l > ra + rb then 0
       else 1
       end
end

0024 Physical Experiments

$<.readlines.map(&:to_r).each do |v|
  puts((1 + 1/98r * v ** 2).ceil)
end

0025 Hit and Blow

$<.readlines.map {|a| a.split.map(&:to_i)}.each_slice(2) do |a, b|
  a1, b1 = [], []
  hit = 0
  a.each_index do |i|
    if a[i] == b[i]
      hit += 1
    else
      a1 << a[i]
      b1 << b[i]
    end
  end
  blow = a1.size - (a1 - b1).size
  puts "#{hit} #{blow}"
end

0026 Dropping Ink

L = 10
table = [a = [[0, 0], [0, -1], [1, 0], [0, 1], [-1, 0]],
         b = a + [[1, -1], [1, 1], [-1, 1], [-1, -1]],
         b + [[0, -2], [2, 0], [0, 2], [-2, 0]]]
field = Array.new(L) {Array.new(L, 0)}

set = ->(x, y) {
  return if x < 0 or x >= L or y < 0 or y >= L
  field[y][x] += 1
}

$<.readlines.map {|l| l.split(",").map(&:to_i)}.each do |x, y, s|
  table[s - 1].each {|dx, dy| set.(x + dx, y + dy)}
end
f = field.flatten
puts f.count(0)
puts f.max

0027 What day is today?

require 'date'
table = %w(Sunday Monday Tuesday Wednesday Thursday Friday Saturday)

loop do
  month, day = $<.gets.split.map(&:to_i)
  break if month.zero?
  puts table[Date.new(2004, month, day).wday]
end

0028 Mode Value

field = Array.new(101, 0)
$<.readlines.map(&:to_i).each {|n| field[n] += 1}
m = field.max
field.each_with_index {|n, i| puts i if m == n}

0029 English Sentence

counts = Hash.new(0)
max = [0, nil]

$<.gets.split.map(&:downcase).each do |word|
  counts[word] += 1
  l = word.length
  max = [l, word] if l > max.first
end
h = counts.invert
puts "#{h[h.keys.max]} #{max.last}"

0030 Sum of Integers

loop do
  n, s = $<.gets.split.map(&:to_i)
  break if n.zero? and s.zero?
  puts [*0..9].combination(n).map {|numbers| numbers.sum == s}.count(true)
end