[中譯] Puzzleup 2011 (04) Code Length

看板puzzle (益智遊戲 - 數獨,拼圖,推理,西洋棋)作者lollygagger (chivalry's alive)時間14年前 (2011/08/23 08:09)推噓1(1推 0噓 3→)

留言4則, 3人參與討論串1/1

題目網址: www.puzzleup.com/2011/puzzle/?222 加分時限: 8/18 7PM - 8/23 7PM 答對可得基本分１００分。答案可上傳５次，每改１次答案從基本分扣２０分。　比賽期間內可隨時上傳答案，加分時限內答對第ｎ天加（６－ｎ）分　　　　　另依題目的難易有額外加分（如有８０％的人這題答錯，答對者加８０分）　　 ◆Digital Watch Each of the 26 letters of the English Alphabet are written on a card.　　 All 26 cards are put in a bag. Cards are drawed from the bag randomly and put together to form codes. Each code must contain three vowels. 　 When third vowel is drawn, we get a legitimate code and stop drawing cards. The opearation is repeated for a long time. What is the expected mean codelength?(The letters A, E, I, O and U are considered as vowels for this question) Note: If needed, use dot as decimal separator, and decimals with up to five places. For example: 12.34567 　英文２６個字母各寫在２６張卡片上放入袋中，從袋中隨機抽取卡片成為密碼。每個密碼須有３個母音，抽到第３個母音表此碼已合理，停止抽卡。　　這樣操作了很長一段時間，問密碼均長的期望值為何？（母音為 A, E, I, O, U。）注意: 如需要可用小數作答，最高可答至小數點後５位。例：12.34567 －－驚覺今年programup都開始一個月了，版上都沒消息是太簡單了所以大家火花掉嗎@ _@a 不過滿適合文組的復習一下概念至少我算得挺開心的哈 -- 沒事多喝水多喝水沒事 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 118.166.67.55 ※ 編輯: lollygagger 來自: 118.166.67.55 (08/23 08:17)