若已知一个栈的入栈序列是1,2,3,…,n，其输出序列为p1,p2,p3,…,pn，若p1=n，则pi为n-i+1。
AIDS’ThreattoAsiaGrows NEWDELHI-Justafewyearsago.Malawasatypicalmiddle-classIndianhousewife.Shecooked,cleanedandlookedafterhertwosmallchildren. Lastyear,herlifetookatragicturn.HerhusbanddiedofAIDS;shewasfoundoutHIV-positive(爱滋病病毒检验呈阳性反应)andhermother-in-lawtookherchildrenawayfromher,sayingtheywouldgetthedisease.“Whenfriendsdroppedforavisit,shewouldintroduceme,saying,‘Sheismyson’swidow.ShehasAIDS,’”saidMala.AIDSisnowdescribedas“explosive(炸药)“aroundtheworld.AstudyofahospitalintheportcityofDurbaninSouthAfrica,wheretheworld’sbiggestandAfrica’sfirstAIDSconferenceopenedlastSunday,foundthatalmosthalfthebedsinmedicalwards(病房)wereoccupiedbyAIDSpatients. SouthAfricahasoneoftheworld’sfastestgrowingHIVinfections(传染),with1,700peopleinfecteddaily,addingtothe4.3million,or10percentofitspopulation,livingwithHIV.Untilnow,AsiahasbeenmoresuccessfulinholdingtheAIDSvirus(病毒)thanAfrica,wherethediseasehaskilledabout12millionpeople. AIDSisnowthreateningtosurroundmanyofAsia’spoverty-strickencountries.CountriesinAsia,suchasCambodia,andThailand,haveHIVinfectionspeedsover1percent.Butthelowspeedshidehugenumbersofaffectedpeople,becauseofthepopulationbase. InIndia,forexample,3.7millionareinfected,morethaninanyothercountryexceptSouthAfrica.InChina,anestimated500,000people,mainlydrugusers,livewithHIV/AIDS.GordonAlexander,asenioadvisorforUNAIDSinIndia,estimates(估计)thatthenumberhitbyAIDSinAsiawillclimbabouteightmillionoverthenextfiveyearsfromaboutsixmillion. InmanyAsiancountries,thebattleagainstHIVisasocialandculturaloneagainstpublicdiscussionofsexualhealthputanationwidemediacampaignintoACTiontolimitthespeedofHIVthroughunsafesex.BrentonWong,anofficialforSingapore’sACTionforAIDS,saystheACTualHIVincidenceinthecitystateof3.9millionpeopleisatleasteighttimeshigherthanofficialdata.”Shameanddenyisstillvery,verycommonsopeopleareafraidtogettestedandmanytimeswon’teventelltheirfamiliesiftheytestpositive,”saidWong.3.Accordingtothepassage,themainreasonsthatAIDSspreadinAsiaisthrough_______.