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  • Java冒泡法和二分法

    最近去一家公司面试,手贱在人家CTO面前自告奋勇写了一把冒泡法,结果在交换数据的时候出了洋相,回家反思,写下如下代码,对自己算是一个鞭策,得到的教训是不要眼高手低,低调前行。

     1 package com.defymedia.interview.sort;
     2 
     3 import java.util.ArrayList;
     4 import java.util.List;
     5 import java.util.Random;
     6 
     7 public class SimpleSort {
     8 
     9     public static final int NO_MATCH = -1;
    10 
    11     public <T extends Comparable> List<T> sort(List<T> list) {
    12         int size = list != null ? list.size() : 0;
    13         if (size == 0) return null;
    14 
    15         for (int i = 0; i < size; i++) {
    16             for (int j = i + 1; j < size; j++) {
    17                 if (list.get(i).compareTo(list.get(j)) > 0) {
    18                     T temp = list.get(i);
    19                     list.set(i, list.get(j));
    20                     list.set(j, temp);
    21                 }
    22             }
    23         }
    24 
    25         return list;
    26     }
    27 
    28     public <T extends Comparable> T[] sort(T[] ts) {
    29         int size = ts != null ? ts.length : 0;
    30         if (size == 0) return null;
    31 
    32         for (int i = 0; i < size; i++) {
    33             for (int j = i + 1; j < size; j++) {
    34                 if (ts[i].compareTo(ts[j]) > 0) {
    35                     T temp = ts[i];
    36                     ts[i] = ts[j];
    37                     ts[j] = temp;
    38                 }
    39             }
    40         }
    41 
    42         return ts;
    43     }
    44 
    45     public <T extends Comparable> int binarySearch(T[] ts, T t) {
    46         int length = ts != null ? ts.length : NO_MATCH;
    47         if (length <= 0 || t == null) return NO_MATCH;
    48 
    49         int middle;
    50         int index = NO_MATCH;
    51         int low = 0;
    52         int high = length;
    53         while (low < high) {
    54             middle = (low + high) >> 1;
    55             T temp = ts[middle];
    56             if (temp.compareTo(t) > 0) {
    57                 high = middle;
    58             } else if (temp.compareTo(t) < 0) {
    59                 low = middle;
    60             } else {
    61                 index = middle;
    62                 break;
    63             }
    64         }
    65 
    66         System.out.println("index is " + index);
    67         return index;
    68     }
    69 
    70     public static void main(String[] param) {
    71         SimpleSort simpleSort = new SimpleSort();
    72         int size = 10;
    73         Random random = new Random();
    74         List<Integer> list = new ArrayList<>(size);
    75         for (int i = 0; i < size; i++) {
    76             list.add(random.nextInt(20));
    77         }
    78         list = simpleSort.sort(list);
    79         for (Comparable comparable : list) {
    80             System.out.println(comparable.toString());
    81         }
    82         Integer[] data = new Integer[size];
    83         for (int i = 0; i < size; i++) {
    84             data[i] = random.nextInt(50);
    85         }
    86         data = simpleSort.sort(data);
    87         for (Comparable comparable : data) {
    88             System.out.println(comparable.toString());
    89         }
    90         int number = NO_MATCH;
    91         simpleSort.binarySearch(data, number);
    92     }
    93 }
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  • 原文地址:https://www.cnblogs.com/budoudou/p/6763698.html
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