解答
#!/usr/bin/env ruby
file = $stdin
lines = file.readlines
file.close
m = lines[0].to_i
n = lines[1].to_i
companies = lines[2, n].map{|x| x.split.map{|y| y.to_i}}
companies.sort!{|a, b| b[0] <=> a[0]}
map_q_to_r = {}
map_q_to_r[0] = 0
left_q_sum = companies.inject(0){|sum, x| sum + x[0]}
for q,r in companies
new_map_q_to_r = {}
for sq, sr in map_q_to_r
next if sq + left_q_sum < m
new_map_q_to_r[sq] = sr
end
for sq, sr in map_q_to_r
if new_map_q_to_r.has_key?(sq + q)
new_map_q_to_r[sq + q] = [map_q_to_r[sq + q], sr + r].min
else
new_map_q_to_r[sq + q] = sr + r
end
end
map_q_to_r = new_map_q_to_r
left_q_sum -= q
end
min_cost = -1
for sq, sr in map_q_to_r
if sq >= m
if min_cost < 0
min_cost = sr
else
min_cost = [min_cost, sr].min
end
end
end
puts min_cost
コードの覚え書き
- 動的計画法で人数をキーにして、その人数での最小コストをメモ化してナップサック問題を解く
- 残りの会社の総人数を加えてもプロジェクトに必要な人数に届かないメモは捨てる