Manipulating string multiple times using Hashmap or toCharArray() method












0














The problem statement is that we have a string and we want to rotate each character to its next character i.e a to b, b to c and z to a. Also, the conversion is based on the number x ( x is <= size of string). The number represents the length of the characters to be converted. Let's say the number is 3 and string is stack which means only first 3 characters need to be converted, so output will be tubck. if the number is 5 then the output will be tubdl.



I am running the solution for 100000000 times and generating the variable number randomly. I have solved this problem using two approaches mentioned below:




  1. Convert from character to integer, then increment the integer by 1, then convert the integer back to character.

  2. Using the hashmap to get the updated character value in O(1) time.


The runtime of the hashmap technique (approach 2) is coming to be more. I don't know why?





Approach #1 is



public static void main(String args) {
Long startTime = System.currentTimeMillis();

String name = "abcdefghijklmnopqrstuvwxyz";
char stringCharArray = name.toCharArray();
Random random = new Random();
for (Integer i = 0; i <100000000; i++) {
{
for (int j = 0; j < random.nextInt(26) + 1; j++) {
if (stringCharArray[j] == 'z') {
stringCharArray[j] = 'a';
} else {
stringCharArray[j] = (char) (((int) (stringCharArray[j])) + 1);
}
}
}
}
Long endtime = System.currentTimeMillis();
System.out.println(endtime-startTime+" ms");

}




Approach # 2 using hashmap is



public static void main(String args) {
HashMap hashMap = new HashMap();
hashMap.put('a', 'b');
hashMap.put('b', 'c');
hashMap.put('c', 'd');
hashMap.put('d', 'e');
hashMap.put('e', 'f');
hashMap.put('f', 'g');
hashMap.put('g', 'h');
hashMap.put('h', 'i');
hashMap.put('i', 'j');
hashMap.put('j', 'k');
hashMap.put('k', 'l');
hashMap.put('l', 'm');
hashMap.put('m', 'n');
hashMap.put('n', 'o');
hashMap.put('o', 'p');
hashMap.put('p', 'q');
hashMap.put('q', 'r');
hashMap.put('r', 's');
hashMap.put('s', 't');
hashMap.put('t', 'u');
hashMap.put('u', 'v');
hashMap.put('v', 'w');
hashMap.put('w', 'x');
hashMap.put('x', 'y');
hashMap.put('y', 'z');
hashMap.put('z', 'a');
Long startTime = System.currentTimeMillis();
String name = "abcdefghijklmnopqrstuvwxyz";
char stringCharArray = name.toCharArray();
Random random = new Random();
for (Integer i = 0; i <100000000; i++) {
{
for (Integer j = 0; j < random.nextInt(26) + 1; j++) {
stringCharArray[j] = (char) hashMap.get(stringCharArray[j]);
}
}
}
Long endtime = System.currentTimeMillis();
System.out.println(endtime-startTime+" ms");
}




The runtime of approach 1 is ~ 8150 ms and approach 2 is ~ 9700 ms. I am using MacBook Pro 2.3 GHz Intel Core i5 with 8 GB 2133 MHz LPDDR3.





How do I reduce this runtime, I used java streams.parallelize to make the changes but the runtime was increasing. What am I doing wrong? The goal is to get the runtime less than approach #1.










share|improve this question









New contributor




Amarjit Singh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

























    0














    The problem statement is that we have a string and we want to rotate each character to its next character i.e a to b, b to c and z to a. Also, the conversion is based on the number x ( x is <= size of string). The number represents the length of the characters to be converted. Let's say the number is 3 and string is stack which means only first 3 characters need to be converted, so output will be tubck. if the number is 5 then the output will be tubdl.



    I am running the solution for 100000000 times and generating the variable number randomly. I have solved this problem using two approaches mentioned below:




    1. Convert from character to integer, then increment the integer by 1, then convert the integer back to character.

    2. Using the hashmap to get the updated character value in O(1) time.


    The runtime of the hashmap technique (approach 2) is coming to be more. I don't know why?





    Approach #1 is



    public static void main(String args) {
    Long startTime = System.currentTimeMillis();

    String name = "abcdefghijklmnopqrstuvwxyz";
    char stringCharArray = name.toCharArray();
    Random random = new Random();
    for (Integer i = 0; i <100000000; i++) {
    {
    for (int j = 0; j < random.nextInt(26) + 1; j++) {
    if (stringCharArray[j] == 'z') {
    stringCharArray[j] = 'a';
    } else {
    stringCharArray[j] = (char) (((int) (stringCharArray[j])) + 1);
    }
    }
    }
    }
    Long endtime = System.currentTimeMillis();
    System.out.println(endtime-startTime+" ms");

    }




    Approach # 2 using hashmap is



    public static void main(String args) {
    HashMap hashMap = new HashMap();
    hashMap.put('a', 'b');
    hashMap.put('b', 'c');
    hashMap.put('c', 'd');
    hashMap.put('d', 'e');
    hashMap.put('e', 'f');
    hashMap.put('f', 'g');
    hashMap.put('g', 'h');
    hashMap.put('h', 'i');
    hashMap.put('i', 'j');
    hashMap.put('j', 'k');
    hashMap.put('k', 'l');
    hashMap.put('l', 'm');
    hashMap.put('m', 'n');
    hashMap.put('n', 'o');
    hashMap.put('o', 'p');
    hashMap.put('p', 'q');
    hashMap.put('q', 'r');
    hashMap.put('r', 's');
    hashMap.put('s', 't');
    hashMap.put('t', 'u');
    hashMap.put('u', 'v');
    hashMap.put('v', 'w');
    hashMap.put('w', 'x');
    hashMap.put('x', 'y');
    hashMap.put('y', 'z');
    hashMap.put('z', 'a');
    Long startTime = System.currentTimeMillis();
    String name = "abcdefghijklmnopqrstuvwxyz";
    char stringCharArray = name.toCharArray();
    Random random = new Random();
    for (Integer i = 0; i <100000000; i++) {
    {
    for (Integer j = 0; j < random.nextInt(26) + 1; j++) {
    stringCharArray[j] = (char) hashMap.get(stringCharArray[j]);
    }
    }
    }
    Long endtime = System.currentTimeMillis();
    System.out.println(endtime-startTime+" ms");
    }




    The runtime of approach 1 is ~ 8150 ms and approach 2 is ~ 9700 ms. I am using MacBook Pro 2.3 GHz Intel Core i5 with 8 GB 2133 MHz LPDDR3.





    How do I reduce this runtime, I used java streams.parallelize to make the changes but the runtime was increasing. What am I doing wrong? The goal is to get the runtime less than approach #1.










    share|improve this question









    New contributor




    Amarjit Singh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.























      0












      0








      0







      The problem statement is that we have a string and we want to rotate each character to its next character i.e a to b, b to c and z to a. Also, the conversion is based on the number x ( x is <= size of string). The number represents the length of the characters to be converted. Let's say the number is 3 and string is stack which means only first 3 characters need to be converted, so output will be tubck. if the number is 5 then the output will be tubdl.



      I am running the solution for 100000000 times and generating the variable number randomly. I have solved this problem using two approaches mentioned below:




      1. Convert from character to integer, then increment the integer by 1, then convert the integer back to character.

      2. Using the hashmap to get the updated character value in O(1) time.


      The runtime of the hashmap technique (approach 2) is coming to be more. I don't know why?





      Approach #1 is



      public static void main(String args) {
      Long startTime = System.currentTimeMillis();

      String name = "abcdefghijklmnopqrstuvwxyz";
      char stringCharArray = name.toCharArray();
      Random random = new Random();
      for (Integer i = 0; i <100000000; i++) {
      {
      for (int j = 0; j < random.nextInt(26) + 1; j++) {
      if (stringCharArray[j] == 'z') {
      stringCharArray[j] = 'a';
      } else {
      stringCharArray[j] = (char) (((int) (stringCharArray[j])) + 1);
      }
      }
      }
      }
      Long endtime = System.currentTimeMillis();
      System.out.println(endtime-startTime+" ms");

      }




      Approach # 2 using hashmap is



      public static void main(String args) {
      HashMap hashMap = new HashMap();
      hashMap.put('a', 'b');
      hashMap.put('b', 'c');
      hashMap.put('c', 'd');
      hashMap.put('d', 'e');
      hashMap.put('e', 'f');
      hashMap.put('f', 'g');
      hashMap.put('g', 'h');
      hashMap.put('h', 'i');
      hashMap.put('i', 'j');
      hashMap.put('j', 'k');
      hashMap.put('k', 'l');
      hashMap.put('l', 'm');
      hashMap.put('m', 'n');
      hashMap.put('n', 'o');
      hashMap.put('o', 'p');
      hashMap.put('p', 'q');
      hashMap.put('q', 'r');
      hashMap.put('r', 's');
      hashMap.put('s', 't');
      hashMap.put('t', 'u');
      hashMap.put('u', 'v');
      hashMap.put('v', 'w');
      hashMap.put('w', 'x');
      hashMap.put('x', 'y');
      hashMap.put('y', 'z');
      hashMap.put('z', 'a');
      Long startTime = System.currentTimeMillis();
      String name = "abcdefghijklmnopqrstuvwxyz";
      char stringCharArray = name.toCharArray();
      Random random = new Random();
      for (Integer i = 0; i <100000000; i++) {
      {
      for (Integer j = 0; j < random.nextInt(26) + 1; j++) {
      stringCharArray[j] = (char) hashMap.get(stringCharArray[j]);
      }
      }
      }
      Long endtime = System.currentTimeMillis();
      System.out.println(endtime-startTime+" ms");
      }




      The runtime of approach 1 is ~ 8150 ms and approach 2 is ~ 9700 ms. I am using MacBook Pro 2.3 GHz Intel Core i5 with 8 GB 2133 MHz LPDDR3.





      How do I reduce this runtime, I used java streams.parallelize to make the changes but the runtime was increasing. What am I doing wrong? The goal is to get the runtime less than approach #1.










      share|improve this question









      New contributor




      Amarjit Singh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      The problem statement is that we have a string and we want to rotate each character to its next character i.e a to b, b to c and z to a. Also, the conversion is based on the number x ( x is <= size of string). The number represents the length of the characters to be converted. Let's say the number is 3 and string is stack which means only first 3 characters need to be converted, so output will be tubck. if the number is 5 then the output will be tubdl.



      I am running the solution for 100000000 times and generating the variable number randomly. I have solved this problem using two approaches mentioned below:




      1. Convert from character to integer, then increment the integer by 1, then convert the integer back to character.

      2. Using the hashmap to get the updated character value in O(1) time.


      The runtime of the hashmap technique (approach 2) is coming to be more. I don't know why?





      Approach #1 is



      public static void main(String args) {
      Long startTime = System.currentTimeMillis();

      String name = "abcdefghijklmnopqrstuvwxyz";
      char stringCharArray = name.toCharArray();
      Random random = new Random();
      for (Integer i = 0; i <100000000; i++) {
      {
      for (int j = 0; j < random.nextInt(26) + 1; j++) {
      if (stringCharArray[j] == 'z') {
      stringCharArray[j] = 'a';
      } else {
      stringCharArray[j] = (char) (((int) (stringCharArray[j])) + 1);
      }
      }
      }
      }
      Long endtime = System.currentTimeMillis();
      System.out.println(endtime-startTime+" ms");

      }




      Approach # 2 using hashmap is



      public static void main(String args) {
      HashMap hashMap = new HashMap();
      hashMap.put('a', 'b');
      hashMap.put('b', 'c');
      hashMap.put('c', 'd');
      hashMap.put('d', 'e');
      hashMap.put('e', 'f');
      hashMap.put('f', 'g');
      hashMap.put('g', 'h');
      hashMap.put('h', 'i');
      hashMap.put('i', 'j');
      hashMap.put('j', 'k');
      hashMap.put('k', 'l');
      hashMap.put('l', 'm');
      hashMap.put('m', 'n');
      hashMap.put('n', 'o');
      hashMap.put('o', 'p');
      hashMap.put('p', 'q');
      hashMap.put('q', 'r');
      hashMap.put('r', 's');
      hashMap.put('s', 't');
      hashMap.put('t', 'u');
      hashMap.put('u', 'v');
      hashMap.put('v', 'w');
      hashMap.put('w', 'x');
      hashMap.put('x', 'y');
      hashMap.put('y', 'z');
      hashMap.put('z', 'a');
      Long startTime = System.currentTimeMillis();
      String name = "abcdefghijklmnopqrstuvwxyz";
      char stringCharArray = name.toCharArray();
      Random random = new Random();
      for (Integer i = 0; i <100000000; i++) {
      {
      for (Integer j = 0; j < random.nextInt(26) + 1; j++) {
      stringCharArray[j] = (char) hashMap.get(stringCharArray[j]);
      }
      }
      }
      Long endtime = System.currentTimeMillis();
      System.out.println(endtime-startTime+" ms");
      }




      The runtime of approach 1 is ~ 8150 ms and approach 2 is ~ 9700 ms. I am using MacBook Pro 2.3 GHz Intel Core i5 with 8 GB 2133 MHz LPDDR3.





      How do I reduce this runtime, I used java streams.parallelize to make the changes but the runtime was increasing. What am I doing wrong? The goal is to get the runtime less than approach #1.







      java performance






      share|improve this question









      New contributor




      Amarjit Singh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      share|improve this question









      New contributor




      Amarjit Singh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









      share|improve this question




      share|improve this question








      edited 2 mins ago





















      New contributor




      Amarjit Singh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









      asked 10 mins ago









      Amarjit Singh

      1011




      1011




      New contributor




      Amarjit Singh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.





      New contributor





      Amarjit Singh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.






      Amarjit Singh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.






















          0






          active

          oldest

          votes











          Your Answer





          StackExchange.ifUsing("editor", function () {
          return StackExchange.using("mathjaxEditing", function () {
          StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
          StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["\$", "\$"]]);
          });
          });
          }, "mathjax-editing");

          StackExchange.ifUsing("editor", function () {
          StackExchange.using("externalEditor", function () {
          StackExchange.using("snippets", function () {
          StackExchange.snippets.init();
          });
          });
          }, "code-snippets");

          StackExchange.ready(function() {
          var channelOptions = {
          tags: "".split(" "),
          id: "196"
          };
          initTagRenderer("".split(" "), "".split(" "), channelOptions);

          StackExchange.using("externalEditor", function() {
          // Have to fire editor after snippets, if snippets enabled
          if (StackExchange.settings.snippets.snippetsEnabled) {
          StackExchange.using("snippets", function() {
          createEditor();
          });
          }
          else {
          createEditor();
          }
          });

          function createEditor() {
          StackExchange.prepareEditor({
          heartbeatType: 'answer',
          autoActivateHeartbeat: false,
          convertImagesToLinks: false,
          noModals: true,
          showLowRepImageUploadWarning: true,
          reputationToPostImages: null,
          bindNavPrevention: true,
          postfix: "",
          imageUploader: {
          brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
          contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
          allowUrls: true
          },
          onDemand: true,
          discardSelector: ".discard-answer"
          ,immediatelyShowMarkdownHelp:true
          });


          }
          });






          Amarjit Singh is a new contributor. Be nice, and check out our Code of Conduct.










          draft saved

          draft discarded


















          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fcodereview.stackexchange.com%2fquestions%2f210794%2fmanipulating-string-multiple-times-using-hashmap-or-tochararray-method%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown

























          0






          active

          oldest

          votes








          0






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes








          Amarjit Singh is a new contributor. Be nice, and check out our Code of Conduct.










          draft saved

          draft discarded


















          Amarjit Singh is a new contributor. Be nice, and check out our Code of Conduct.













          Amarjit Singh is a new contributor. Be nice, and check out our Code of Conduct.












          Amarjit Singh is a new contributor. Be nice, and check out our Code of Conduct.
















          Thanks for contributing an answer to Code Review Stack Exchange!


          • Please be sure to answer the question. Provide details and share your research!

          But avoid



          • Asking for help, clarification, or responding to other answers.

          • Making statements based on opinion; back them up with references or personal experience.


          Use MathJax to format equations. MathJax reference.


          To learn more, see our tips on writing great answers.





          Some of your past answers have not been well-received, and you're in danger of being blocked from answering.


          Please pay close attention to the following guidance:


          • Please be sure to answer the question. Provide details and share your research!

          But avoid



          • Asking for help, clarification, or responding to other answers.

          • Making statements based on opinion; back them up with references or personal experience.


          To learn more, see our tips on writing great answers.




          draft saved


          draft discarded














          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fcodereview.stackexchange.com%2fquestions%2f210794%2fmanipulating-string-multiple-times-using-hashmap-or-tochararray-method%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown





















































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown

































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown







          Popular posts from this blog

          404 Error Contact Form 7 ajax form submitting

          How to know if a Active Directory user can login interactively

          TypeError: fit_transform() missing 1 required positional argument: 'X'