程式設計練習3

找出小於120的所有孿生質數(twin prime)

程式設計練習2

String X=" What  test is that? this is a....."
1.去掉空格
2. 取子字串4~21
3. this->這, is->是, a->一個, test->嘗試
4. 改大寫
5. 字串反轉
6. 將字串2,4,6,8,10,.....的字元組成一新字串

程式設計練習1

請用SecureRandom產生100個整數亂數值為[0,9]。 請計算每個數值出現的次數。

RSA cipher解密

解回明文

import java.math.BigInteger;

public class ex2 {

 public static void main(String[] args) {
  BigInteger n=new BigInteger("5375388922978628413155272656747327652336395530199103021900839849090732075550437233179766702787100243937175380405082366985570014906877346763928089904752147");
  BigInteger d=new BigInteger("3562336077709646293856410845969831535184737018515713275359421306058446640504285015571117411667368274571293441355632153687264610437891764149716318547851669");
  BigInteger c=new BigInteger("4646214319130296784626336389218304062490256344497824318351606042291236051054052316596982428177153055110734920639810028422212513692377137973131254994553255");
 }

}