果然挺2的~~

是真2···

谁2

恩。。。相当的。。。上班没前途。。。那些职业经理人都可以自挂东南枝了。。
2.。。。绝对的

羽毛 哥们求助！！

比我还2了？

浅评某些无知少年的2言2行2脑子

小考你的生意我不接。。。你找别人吧

日你奶奶 你Java强么

贝勒。。。。他绝对比你还2.。。。。只有更2没有最2~

- -！
谁呀？
我曾经以为自己是最二的人
经你们这么一说
我倒成聪明人了！

我不告诉你。。。。要淡定的含蓄。。。。小考到底咋了。啥事。。快点说。。

帮我看一个极其sb的程序 要求：读入一个二进制文件 进行文件大小/2次数的实验 实验内容随机产生两个数字 然后去文件中相应位置找到两个字符 如果两个字符相等 算成功一次 最后用成功次数/文件大小算出概率

import java.io.*;
import java.util.*;
public class Lab_Part_B
{
public static void main(String[] args) throws Exception
{
String file = args[0];
FileInputStream fis = new FileInputStream(file);
int size = fis.available();
int plain_size = 0;
int count = 0, r1 = 0, r2 = 0, c1 = 0, c2 = 0;
double p = 0.00;
Random generator = new Random();
String plain_text = new String();
for (int i = 0; i < size; i++)
{
char temp_char =(char) fis.read();
plain_text = plain_text + temp_char;
}
plain_size = plain_text.length();
for (int i = 0; i <= plain_size/2; i++)
{
do {
r1 = generator.nextInt(plain_size);
r2 = generator.nextInt(plain_size);
}while(r1 == r2);
c1 =(int)plain_text.charAt(r1);
c2 =(int)plain_text.charAt(r2);
if (c1 == c2) {
count++;
}
}
p = (double) count/plain_size;
System.out.print(p);
fis.close();
}
}

哦。。。刚好最近带了一个河工大的JAVA培训班。。让他们当课后思考题吧

教授说概率在6-7之间 我只能算到3-4之间

算了 我自己搞吧

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NINGOPERATIONSWHICHPRODUCEATHIRDSYSTEMFROMTWOGIVENSYSTEMSTHERSTCOMBININGOPERATIONISCALLEDTHEPRODUCTOPERATIONANDCORRESPONDSTOENCIPHERINGTHEMESSAGEWITHTHERSTSECRECYSYSTEMRANDENCIPHERINGTHERESULTINGCRYPTOGRAMWITHTHESECONDSYSTEMSTHEKEYSFORRANDSBEINGCHOSENINDEPENDENTLYTHISTOTALOPERATIONISASECRECYSYSTEMWHOSETRANSFORMATIONSCONSISTOFALLTHEPRODUCTSINTHEUSUALSENSEOFPRODUCTSOFTRANSFORMATIONSOFTRANSFORMATIONSINSWITHTRANSFORMATIONSINRTHEPROBABILITIESARETHEPRODUCTSOFTHEPROBABILITIESFORTHETWOTRANSFORMATIONSTHESECONDCOMBININGOPERATIONISWEIGHTEDADDITIONTPRQSPQITCORRESPONDSTOMAKINGAPRELIMINARYCHOICEASTOWHETHERSYSTEMRORSISTOBEUSEDWITHPROBABILITIESPANDQRESPECTIVELYWHENTHISISDONERORSISUSEDASORIGINALLYDENEDITISSHOWNTHATSECRECYSYSTEMSWITHTHESETWOCOMBININGOPERATIONSFORMESSENTIALLYALINEARASSOCIATIVEALGEBRAWITHAUNITELEMENTANALGEBRAICVARIETYTHATHASBEENEXTENSIVELYSTUDIEDBYMATHEMATICIANSAMONGTHEMANYPOSSIBLESECRECYSYSTEMSTHEREISONETYPEWITHMANYSPECIALPROPERTIESTHISTYPEWECALLAPURESYSTEMASYSTEMISPUREIFALLKEYSAREEQUALLYLIKELYANDIFFORANYTHREETRANSFORMATIONSTITJTKINTHESETTHEPRODUCTTITJTKISALSOATRANSFORMATIONINTHESETTHATISENCIPHERINGDECIPHERINGANDENCIPHERINGWITHANYTHREEKEYSMUSTBEEQUIVALENTTOENCIPHERINGWITHSOMEKEYWITHAPURECIPHERITISSHOWNTHATALLKEYSAREESSENTIALLYEQUIVALENTTHEYALLLEADTOTHESAMESETOFAPOSTERIORIPROBABILITIESFURTHERMOREWHENAGIVENCRYPTOGRAMISINTERCEPTEDTHEREISASETOFMESSAGESTHATMIGHTHAVEPRODUCEDTHISCRYPTOGRAMARESIDUECLASSANDTHEAPOSTERIORIPROBABILITIESOFMESSAGEINTHISCLASSAREPROPORTIONALTOTHEAPRIORIPROBABILITIESALLTHEINFORMATIONTHEENEMYHASOBTAINEDBYINTERCEPTINGTHECRYPTOGRAMISASPECICATIONOFTHERESIDUECLASSMANYOFTHECOMMONCIPHERSAREPURESYSTEMSINCLUDINGSIMPLESUBSTITUTIONWITHRANDOMKEYINTHISCASETHERESIDUECLASSCONSISTSOFALLMESSAGESWITHTHESAMEPATTERNOFLETTERREPETITIONSASTHEINTERCEPTEDCRYPTOGRAMTWOSYSTEMSRANDSAREDENEDTOBESIMILARIFTHEREEXISTSAXEDTRANSFORMATIONAWITHANINVERSEASUCHTHATRASIFRANDSARESIMILARAONETOONECORRESPONDENCEBETWEENTHERESULTINGCRYPTOGRAMSCANBESETUPLEADINGTOTHESAMEAPOSTERIORIPROBABILITIESTHETWOSYSTEMSARECRYPTANALYTICALLYTHESAMETHESECONDPARTOFTHEPAPERDEALSWITHTHEPROBLEMOFTHEORETICALSECRECYHOWSECUREISASYSTEMAGAINSTCRYPTANALYSISWHENTHEENEMYHASUNLIMITEDTIMEANDMANPOWERAVAILABLEFORTHEANALYSISOFINTERCEPTEDCRYPTOGRAMSTHEPROBLEMISCLOSELYRELATEDTOQUESTIONSOFCOMMUNICATIONINTHEPRESENCEOFNOISEANDTHECONCEPTSOFENTROPYANDEQUIVOCATIONDEVELOPEDFORTHECOMMUNICATIONPROBLEMNDADIRECTAPPLICATIONINTHISPARTOFCRYPTOGRAPHYPERFECTSECRECYISDENEDBYREQUIRINGOFASYSTEMTHATAFTERACRYPTOGRAMISINTERCEPTEDBYTHEENEMYTHEAPOSTERIORIPROBABILITIESOFTHISCRYPTOGRAMREPRESENTINGVARIOUSMESSAGESBEIDENTICALLYTHESAMEASTHEAPRIORIPROBABILITIESOFTHESAMEMESSAGESBEFORETHEINTERCEPTIONITISSHOWNTHATPERFECTSECRECYISPOSSIBLEBUTREQUIRESIFTHENUMBEROFMESSAGESISNITETHESAMENUMBEROFPOSSIBLEKEYSIFTHEMESSAGEISTHOUGHTOFASBEINGCONSTANTLYGENERATEDATAGIVENRATERTOBEDENEDLATERKEYMUSTBEGENERATEDATTHESAMEORAGREATERRATEIFASECRECYSYSTEMWITHANITEKEYISUSEDANDNLETTERSOFCRYPTOGRAMINTERCEPTEDTHEREWILLBEFORTHEENEMYACERTAINSETOFMESSAGESWITHCERTAINPROBABILITIESTHATTHISCRYPTOGRAMCOULDREPRESENTASNINCREASESTHEELDUSUALLYNARROWSDOWNUNTILEVENTUALLYTHEREISAUNIQUESOLUTIONTOTHECRYPTOGRAMONEMESSAGEWITHPROBABILITYESSENTIALLYUNITYWHILEALLOTHERSAREPRACTICALLYZEROAQUANTITYHNISDENEDCALLEDTHEEQUIVOCATIONWHICHMEASURESINASTATISTICALWAYHOWNEARTHEAVERAGECRYPTOGRAMOFNLETTERSISTOAUNIQUESOLUTIONTHATISHOWUNCERTAINTHEENEMYISOFTHEORIGINALMESSAGEAFTERINTERCEPTINGACRYPTOGRAMOFNLETTERSVARIOUSPROPERTIESOFTHEEQUIVOCATIONAREDEDUCEDFOREXAMPLETHEEQUIVOCATIONOFTHEKEYNEVERINCREASESWITHINCREASINGNTHISEQUIVOCATIONISATHEORETICALSECRECYINDEXTHEORETICALINTHATITALLOWSTHEENEMYUNLIMITEDTIMETOANALYSETHECRYPTOGRAMTHEFUNCTIONHNFORACERTAINIDEALIZEDTYPEOFCIPHERCALLEDTHERANDOMCIPHERISDETERMINEDWITHCERTAINMODICATIONSTHISFUNCTIONCANBEAPPLIEDTOMANYCASESOFPRACTICALINTERESTTHISGIVESAWAYOFCALCULATINGAPPROXIMATELYHOWMUCHINTERCEPTEDMATERIALISREQUIREDTOOBTAINASOLUTIONTOASECRECYSYSTEMITAPPEARSFROMTHISANALYSISTHATWITHORDINARYLANGUAGESANDTHEUSUALTYPESOFCIPHERSNOTCODESTHISUNICITYDISTANCEISAPPROXIMATELYHKHEREHKISANUMBERMEASURINGTHESIZEOFTHEKEYSPACEDIFALLKEYSAREAPRIORIEQUALLYLIKELYHKISTHELOGARITHMOFTHENUMBEROFPOSSIBLEKEYSDISTHEREDUNDANCYOFTHELANGUAGEANDMEASURESTHEAMOUNTOFSTATISTICALCONSTRAINTIMPOSEDBYTHELANGUAGEINSIMPLESUBSTITUTIONWITHRANDOMKEYHKISLOGORABOUTANDDINDECIMALDIGITSPERLETTERISABOUTFORENGLISHTHUSUNICITYOCCURSATABOUTLETTERSITISPOSSIBLETOCONSTRUCTSECRECYSYSTEMSWITHANITEKEYFORCERTAINLANGUAGESINWHICHTHEEQUIVOCATIONDOESNOTAPPROACHZEROASNINTHISCASENOMATTERHOWMUCHMATERIALISINTERCEPTEDTHEENEMYSTILLDOESNOTOBTAINAUNIQUESOLUTIONTOTHECIPHERBUTISLEFTWITHMANYALTERNATIVESALLOFREASONABLEPROBABILITYSUCHSYSTEMSWECALLIDEALSYSTEMSITISPOSSIBLEINANYLANGUAGETOAPPROXIMATESUCHBEHAVIORIETOMAKETHEAPPROACHTOZEROOFHNRECEDEOUTTOARBITRARILYLARGENHOWEVERSUCHSYSTEMSHAVEANUMBEROFDRAWBACKSSUCHASCOMPLEXITYANDSENSITIVITYTOERRORSINTRANSMISSIONOFTHECRYPTOGRAMTHETHIRDPARTOFTHEPAPERISCONCERNEDWITHPRACTICALSECRECYTWOSYSTEMSWITHTHESAMEKEYSIZEMAYBOTHBEUNIQUELYSOLVABLEWHENNLETTERSHAVEBEENINTERCEPTEDBUTDIFFERGREATLYINT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EMESSAGESASMERELYANABSTRACTSETOFENTITIESWITHASSOCIATEDPROBABILITIESNOTNECESSARILYCOMPOSEDO