英语翻译
and movement has long been used to measure time.For example,the ball clock is a simple device which keeps track of the passing minutes by moving ball-bearings.Each minute,a rotating arm removes a ball bearing from the queue at the bottom,raises it to the top of the clock and deposits it on a track leading to indicators displaying minutes,five-minutes and hours.These indicators display the time between 1:00 and 12:59,but without 'a.m.' or 'p.m.' indicators.Thus 2 balls in the minute indicator,6 balls in the five-minute indicator and 5 balls in the hour indicator displays the time 5:32.
Unfortunately,most commercially available ball clocks do not incorporate a date indication,although this would be simple to do with the addition of further carry and indicator tracks.However,all is not lost!As the balls migrate through the mechanism of the clock,they change their relative ordering in a predictable way.Careful study of these orderings will therefore yield the time elapsed since the clock had some specific ordering.The length of time which can be measured is limited because the orderings of the balls eventually begin to repeat.Your program must compute the time before repetition,which varies according to the total number of balls present.
Operation of the Ball Clock
Every minute,the least recently used ball is removed from the queue of balls at the bottom of the clock,elevated,then deposited on the minute indicator track,which is able to hold four balls.When a fifth ball rolls on to the minute indicator track,its weight causes the track to tilt.The four balls already on the track run back down to join the queue of balls waiting at the bottom in reverse order of their original addition to the minutes track.The fifth ball,which caused the tilt,rolls on down to the five-minute indicator track.This track holds eleven balls.The twelfth ball carried over from the minutes causes the five-minute track to tilt,returning the eleven balls to the queue,again in reverse order of their addition.The twelfth ball rolls down to the hour indicator.The hour indicator also holds eleven balls,but has one extra fixed ball which is always present so that counting the balls in the hour indicator will yield an hour in the range one to twelve.The twelfth ball carried over from the five-minute indicator causes the hour indicator to tilt,returning the eleven free balls to the queue,in reverse order,before the twelfth ball itself also returns to the queue