مساله:
برای ساخت رشته رمزگذاری شده:
هر کاراکتر دوم را از رشته بردارید، سپس کاراکترهای دیگر را که هر کاراکتر دوم نیستند ، بردارید و آنها را به عنوان رشته جدید به هم متصل کنید.
این کار را n بار انجام دهید!
برای مثال:
"This is a test!", 1 -> "hsi etTi sats!" "This is a test!", 2 -> "hsi etTi sats!" -> "s eT ashi tist!"
Description:
For building the encrypted string:
Take every 2nd char from the string, then the other chars, that are not every 2nd char, and concat them as new String.
Do this n times!
Examples:
"This is a test!", 1 -> "hsi etTi sats!" "This is a test!", 2 -> "hsi etTi sats!" -> "s eT ashi tist!"
Write two methods:
String encrypt(final String text, final int n) String decrypt(final String encryptedText, final int n)
For both methods:
If the input-string is null or empty return exactly this value!
If n is <= 0 then return the input text.
public class Kata {
public static String encrypt(final String text, final int n) {
String result = text;
int count = n;
while (count > 0) {
String oneTh = "", twoTh = "";
String[] arr = result.split("");
for (int i = 0; i < result.length(); i++) {
if (i % 2 == 0)
oneTh += arr[i];
else
twoTh += arr[i];
}
result = twoTh + oneTh;
count--;
}
return result;
}
public static String decrypt(final String encryptedText, final int n) {
String result = encryptedText;
int count = n;
while (count > 0) {
int length = result.length();
int center = length / 2;
String first = result.substring(0, center);
String second = result.substring(center);
result = "";
for (int i = 0; i < center; i++) {
result += second.split("")[i];
result += first.split("")[i];
}
if (second.length() > center)
result += second.split("")[second.length() - 1];
count--;
}
return result;
}
}public class Kata {
public static String encrypt(final String text, int n) {
if (n <= 0 || text == null || text.isEmpty()) {
return text;
}
StringBuilder firstPart = new StringBuilder();
StringBuilder secondPart = new StringBuilder();
for (int i = 0; i < text.length(); i++) {
char aChar = text.charAt(i);
if (i % 2 == 1) {
firstPart.append(aChar);
} else {
secondPart.append(aChar);
}
}
return encrypt(firstPart.append(secondPart).toString(), --n);
}
public static String decrypt(final String encryptedText, int n) {
if (n <= 0 || encryptedText == null || encryptedText.isEmpty()) {
return encryptedText;
}
StringBuilder text = new StringBuilder();
final int half = encryptedText.length() / 2;
for (int i = 0; i < half; i++) {
text.append(encryptedText.charAt(half + i)).append(encryptedText.charAt(i));
}
if (encryptedText.length() % 2 == 1) {
text.append(encryptedText.charAt(encryptedText.length() - 1));
}
return decrypt(text.toString(), --n);
}
}public class Kata {
public static String encrypt(final String text, final int n) {
String out=text;
for(int i=0; i<n; i++) {
String temp="";
for(int j=1; j<out.length(); j+=2) temp+=out.charAt(j);
for(int j=0; j<out.length(); j+=2) temp+=out.charAt(j);
out=temp;
}
return out;
}
public static String decrypt(final String encryptedText, final int n) {
String out=encryptedText;
for(int i=0; i<n; i++) {
String temp="";
for(int j=0; j<out.length()/2; j+=1) temp+=""+out.charAt(out.length()/2+j)+out.charAt(j);
out=temp+encryptedText.substring(encryptedText.length()/2*2);
}
return out;
}
}import java.util.*;
public class Kata {
public static String encrypt(final String text, final int n) {
if (text == null || text.isEmpty() || n < 1) return text;
return encrypt(text.replaceAll("(.)(.)?", "$2") + text.replaceAll("(.)(.)?", "$1"), n - 1);
}
public static String decrypt(final String text, final int n) {
if (text == null || text.isEmpty() || n < 1) return text;
StringBuilder output = new StringBuilder();
Iterator<String> first = Arrays.asList(text.substring(0, text.length()/2).split("")).iterator();
Iterator<String> last = Arrays.asList(text.substring(text.length()/2).split("")).iterator();
while (first.hasNext() || last.hasNext()) {
if (last.hasNext()) output.append(last.next());
if (first.hasNext()) output.append(first.next());
}
return decrypt(output.toString(), n - 1);
}
}import java.util.stream.IntStream;
import java.util.stream.Collectors;
import java.util.Arrays;
public class Kata {
public static String encrypt(final String text, final int n) {
if(text == null || n < 1) return text;
String first = IntStream.range(0, text.length())
.filter(i -> i%2 == 1)
.mapToObj(i -> text.charAt(i))
.map(Object::toString)
.collect(Collectors.joining(""));
String second = IntStream.range(0, text.length())
.filter(i -> i%2 == 0)
.mapToObj(i -> text.charAt(i))
.map(Object::toString)
.collect(Collectors.joining(""));
return encrypt(first + second, n - 1);
}
public static String decrypt(final String text, final int n) {
if(text == null || n < 1) return text;
String decrypted = IntStream.range(0, text.length())
.mapToObj(i -> (i%2 == 1) ? text.charAt(i/2) : text.charAt(text.length()/2 + i/2))
.map(Object::toString)
.collect(Collectors.joining(""));
return decrypt(decrypted, n - 1);
}
}public class Kata {
public static String encrypt(final String text, final int n) {
if (n<=0) return text;
StringBuilder str = new StringBuilder();
for (int i=1; i<text.length(); i+=2)
str.append(text.substring(i,i+1));
for (int i=0; i<text.length(); i+=2)
str.append(text.substring(i,i+1));
return (n==1)? str.toString() : encrypt(str.toString(), n-1);
}
public static String decrypt(final String entext, final int n) {
if (n<=0) return entext;
StringBuilder str = new StringBuilder();
str.append(entext.substring(0,entext.length()/2));
for (int i=entext.length()/2, j=0; i<entext.length(); i++, j+=2)
str.insert(j,entext.substring(i,i+1));
return (n==1)? str.toString() : decrypt(str.toString(),n-1);
}
}public class Kata {
public static String encrypt(final String text, final int n) {
if(text == null || text == "" || n <= 0)return text;
int half = text.length()/2;
StringBuilder front = new StringBuilder(half);
StringBuilder back = new StringBuilder(half);
for(int i = 0;i<text.length();i++){
if((i & 1) == 1){
front.append(text.charAt(i));
}else{
back.append(text.charAt(i));
}
}
return encrypt(front.append(back.toString()).toString(),n-1);
}
public static String decrypt(final String text, final int n) {
if(text == null || text == "" || n <= 0)return text;
int half = text.length()/2;
StringBuilder result = new StringBuilder(text.length());
int x = 0,y = 0;
for(int i = 0;i<text.length();i++){
if((i & 1) == 1){
result.append(text.charAt(x++));
}else{
result.append(text.charAt(half + y++));
}
}
return decrypt(result.toString(),n-1);
}
}
