复杂的理发店问题。有一个理发店，有m个理发师，店内配置了m个理发椅，分别与理发师一一对应；此外还配置了n个等待席，供顾客在店内等候理发。一旦等候的顾客坐满等候席，只能在门外排队等候进入理发店。试用P、V操作来实现能够保证顾客原则上先来先理发的秩序。要求明确指明顾客进入理发店的时刻、进入理发过程的时刻。这时，需要(23)。

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Structured　programming　practices(71)rise　to　Pascal,　in　which　constructs　were　introduced　to　make　programs　more　readable　and　better(72)C　provided　a　combination　of　assembly　and　high　-level　　structure　to　create　a　general　-purpose　language　that　could　be　used　from　system　to(73)programming.　　Next　came　object　orientation,　which　is(74)of　a　metrology　and　design　philosophy　than　a　language　　issue.　This　is(75)by　the　addition　of　so　-　called　OO　extensions　to　current　language,　such　as　C++.

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Application　development　increasingly　means　Windows　development,　and　the　popularity　of　visual　development　tools　has(66)in　tandem　with　Windows　itself.　These　tools　create　beautiful　windows　wing(67)and　their　fast　development　cycles　and　easy　learning　curves　make　them　a　good(68)for　many　types　of　PC　development　projects.　Today's　developers　are　leveraging　these　tools　and　the　abundance　of　cheap,　powerful　PCs　to　shift　the　balance　of　power　to　the　desktop.　As　the　world　moves　inexorable　toward　Window　and　other(69).　user　interfaces,　developers　can　choose　from　an　abundance　of(70)oriented　tools.　Popular　examples　include　Microsoft　Corp's　Visual　Basic,　powersoft　Corp's　PowerBuilder,　Gupta　Technology　Corp's　SQL　Windows,　and　so　on.