[問題] 手機螢幕鎖
◎ ◎ ◎
◎ ◎ ◎
◎ ◎ ◎
我的moto手機有種圖形螢幕鎖,它的設計是使用者劃過螢幕連接起九宮格中的若干點
作為密碼。
>> 例如
◎→◎→◎ ◎→◎ ◎
↓ ↓
◎ ◎ ◎ 或 ◎ ◎→◎
↖↓ ↓↖ ↓
◎ ◎ ◎ ◎ ◎←◎
都是有效的密碼
它還允許A-B(還有B-C)這樣的連線
◎ ◎ B
┌----┘
A ◎ ◎
◎ C ◎
然而如下圖,a到c中間一定要經過b不能跳過
a ◎ ◎
◎ b ◎
◎ ◎ c
請問至少包含四個點的密碼有幾種?1.旋/翻轉視為不同
2.旋/翻轉視為相同
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※ jurian0101:轉錄至看板 Math 08/19 21:09
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1 2 3
4 5 6
7 8 9
話說Math板有人提醒,我才發現Android的正版螢幕鎖允許2-5-8-6---4這樣的連結
不想改了直接無視。搞操煩啦!!
這裡就當作禁止出現 13/17/19/31/37/39/71/73/79/91/93/97/46/64/82/28 這16個
"規則"好了
LPH66和Favonia一定同意 :D
- - -
Mathematica: 以下為Input
set = Permutations[{"1", "2", "3", "4", "5", "6", "7", "8", "9"}, {4, 9}];
(*生出排列*)
stringset = Array[StringJoin[set[[#]]] &, Length[set]];
(*更改一下形式*)
S[x_, y_] := StringMatchQ[x, y];
(*只是嫌函數太長的代換*)
rule = Not[#] & /@ (S[#, ___ ~~ "13" ~~ ___] ||
S[#, ___ ~~ "17" ~~ ___] || S[#, ___ ~~ "19" ~~ ___] ||
S[#, ___ ~~ "31" ~~ ___] || S[#, ___ ~~ "37" ~~ ___] ||
S[#, ___ ~~ "39" ~~ ___] || S[#, ___ ~~ "71" ~~ ___] ||
S[#, ___ ~~ "73" ~~ ___] || S[#, ___ ~~ "79" ~~ ___] ||
S[#, ___ ~~ "91" ~~ ___] || S[#, ___ ~~ "93" ~~ ___] ||
S[#, ___ ~~ "97" ~~ ___] || S[#, ___ ~~ "28" ~~ ___] ||
S[#, ___ ~~ "82" ~~ ___] || S[#, ___ ~~ "46" ~~ ___] ||
S[#, ___ ~~ "64" ~~ ___] & /@ stringset);
(*將16個規則map到stringset,再取Not*)
Length[Pick[stringset, rule]]
(*Pick根據rule把stringset裡所有「不犯規」的組合挑出來,以利萬一要揪錯所用,
輸出挑出來集合的大小*)
※ 編輯: jurian0101 來自: 218.164.5.102 (08/22 19:07)
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