How many times will the clock(四位显示的电子钟) display three or more of the same number' \6 {# b2 d, B/ W
in a row over the course of one day?
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9 a& O& Z% |8 p/ g- ~3 Q$ y! FIn case you were wondering ,the clock in this puzzle displays time on a 12-hour scale4 l, X2 `. E5 \8 l8 @
not on military time. l+ P; Y1 u6 g9 \; i6 C0 m* a
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我是这样做的: ) T! G* M8 K* J9 X) [- f
aa:aa型 : 2种(00:00,11:11) ( P! F" b( f( I/ P
aa:ab型 : 9*2种 + h W; K# ^) S0 w+ n2 X2 s* B
aa:ba型 : 5*2种- W/ ~, Y. N& I
ab:aa型 : 1+9种(当 a=1时 b不=2,因为在12小时的显示中,没有12:XX这样的时间显示)0 S5 v- i' J! }2 v! U" E1 _" O
ba:aa型 : 5+1种 7 M" F, Q9 U1 ^2 ?
; E9 V, k6 A, g6 H总共46种 .考虑到a.m. p.m.总数*2=92种
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但答案不对 ,网上答案说是34种, 偶郁闷了~
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这个题到底怎么搞? |