SortAndPruneComposites xref

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    1   /**
    2    * Copyright (c) 2004-2011 QOS.ch
    3    * All rights reserved.
    4    *
    5    * Permission is hereby granted, free  of charge, to any person obtaining
    6    * a  copy  of this  software  and  associated  documentation files  (the
    7    * "Software"), to  deal in  the Software without  restriction, including
    8    * without limitation  the rights to  use, copy, modify,  merge, publish,
    9    * distribute,  sublicense, and/or sell  copies of  the Software,  and to
    10   * permit persons to whom the Software  is furnished to do so, subject to
    11   * the following conditions:
    12   *
    13   * The  above  copyright  notice  and  this permission  notice  shall  be
    14   * included in all copies or substantial portions of the Software.
    15   *
    16   * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
    17   * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
    18   * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
    19   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
    20   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    21   * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
    22   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    23   *
    24   */
    25  package org.slf4j.profiler;
    26
    27  import java.util.ArrayList;
    28  import java.util.Arrays;
    29
    30  public class SortAndPruneComposites {
    31
    32    static String NESTED_PROFILER_NAME = "SORT_AND_PRUNE";
    33
    34    final int[] originalArray;
    35    final int originalArrrayLength;
    36
    37    public SortAndPruneComposites(int[] randomArray) {
    38      this.originalArray = randomArray;
    39      this.originalArrrayLength = randomArray.length;
    40
    41    }
    42
    43    public int[] sortAndPruneComposites() {
    44      // retrieve previously registered profiler named "SORT_AND_PRUNE"
    45      ProfilerRegistry profilerRegistry = ProfilerRegistry.getThreadContextInstance();
    46      Profiler sortProfiler = profilerRegistry.get(NESTED_PROFILER_NAME);
    47
    48      // start a new stopwatch called SORT
    49      sortProfiler.start("SORT");
    50      int[] sortedArray = sort();
    51      // start a new stopwatch called PRUNE_COMPOSITES
    52      sortProfiler.start("PRUNE_COMPOSITES");
    53      int result[] = pruneComposites(sortedArray);
    54
    55      return result;
    56    }
    57
    58    private int[] sort() {
    59      int[] sortedArray = new int[originalArrrayLength];
    60      System.arraycopy(originalArray, 0, sortedArray, 0, originalArrrayLength);
    61      Arrays.sort(sortedArray);
    62      return sortedArray;
    63    }
    64
    65    int[] pruneComposites(int[] sortedArray) {
    66      ArrayList<Integer> primesArray = new ArrayList<Integer>();
    67      for(int i = 0; i < originalArrrayLength; i++) {
    68        int n = sortedArray[i];
    69        if(isPrime(n)) {
    70          primesArray.add(n);
    71        }
    72      }
    73      int resultSize = primesArray.size();
    74      int[] result = new int[resultSize];
    75
    76      for(int i = 0; i < resultSize; i++) {
    77        result[i] = primesArray.get(i);
    78      }
    79      return result;
    80    }
    81
    82    public boolean isPrime(int n) {
    83      if(n < 2) {
    84        return false;
    85      }
    86      if(n%2 == 0) {
    87        return false;
    88      }
    89      for(int i = 3; i*i <=n; i += 2) {
    90        if(n%i ==0) {
    91          return false;
    92        }
    93      }
    94      return true;
    95    }
    96  }