素数判定
力技でアルゴリズムもクソもないけど。一応動いたので記録
def prime?(num) return false if [0,1].include?(num) return true if num == 2 max = num - 1 (2..max).each do |i| return false if num % i == 0 end true end #動作検証コード (0..100).each do |i| if prime?(i) if [2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97].include?(i) p "success => #{i}" else p "wrong number => #{i}" end end end #実行結果 "success => 2" "success => 3" "success => 5" "success => 7" "success => 11" "success => 13" "success => 17" "success => 19" "success => 23" "success => 29" "success => 31" "success => 37" "success => 41" "success => 43" "success => 47" "success => 53" "success => 59" "success => 61" "success => 67" "success => 71" "success => 73" "success => 79" "success => 83" "success => 89" "success => 97"