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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  }