小白初识 - 基数排序（RadixSort）

  1 package com.structure.sort;
  2 
  3 /**
  4  * @author zhangxingrui
  5  * @create 2019-01-30 14:58
  6  **/
  7 public class RadixSort {
  8 
  9     public static void main(String[] args) {
 10         /*int[] numbers = {19, 36, 24, 10, 9, 29, 1, 0, 3, 60, 100, 1001, 999, 520, 123, 96};
 11         radixSort(numbers);
 12         for (int number : numbers) {
 13             System.out.println(number);
 14         }*/
 15 
 16         String[] words = {"Java", "Mongodb", "Redis", "Kafka", "javascript", "mysql", "mybatis", "kindle", "rpc", "Algorithm", "mergeSort", "quickSort", "Adobe"};
 17 //        String[] words = {"Java", "mongodb", "Kafka"};
 18         radixSort(words);
 19         for (String word : words) {
 20             System.out.println(word.replaceAll("0", ""));
 21         }
 22     }
 23 
 24     /**
 25      * @Author: xingrui
 26      * @Description: 基数排序（单词）
 27      * @Date: 15:53 2019/1/30
 28      */
 29     private static void radixSort(String[] words){
 30         int exp = 0;
 31         int maxLength = getMaxLength(words);
 32         autoComplete(words, maxLength);
 33         for(exp = 1; exp <= maxLength; exp++){
 34             countingSort(words, exp);
 35         }
 36     }
 37 
 38     /**
 39      * @Author: xingrui
 40      * @Description: 计数排序（单词）
 41      * @Date: 13:57 2019/1/30
 42      */
 43     private static void countingSort(String[] words, int exp){
 44         int n = words.length;
 45         String[] r = new String[n];
 46         int[] c = new int[122];
 47 
 48         for(int i = 0; i < n; ++i){
 49             int asc = (byte)words[i].charAt(words[i].length() - exp);
 50             c[asc]++;
 51         }
 52 
 53         for(int i = 1; i < 122; ++i){
 54             c[i] = c[i-1] + c[i];
 55         }
 56 
 57         for (int i = n - 1; i >= 0; --i){
 58             int asc = (byte)words[i].charAt(words[i].length() - exp);
 59             int index = c[asc];
 60             r[index - 1] = words[i];
 61             c[asc]--;
 62         }
 63 
 64         for(int i = 0; i < n; ++i){
 65             words[i] = r[i];
 66         }
 67     }
 68 
 69     /**
 70      * @Author: xingrui
 71      * @Description: 基数排序（纯数字）
 72      * @Date: 15:00 2019/1/30
 73      */
 74     private static void radixSort(int[] numbers){
 75         int exp = 0;
 76         int maxNumber = getMaxNumber(numbers);
 77         for(exp = 1; maxNumber/exp > 0; exp *= 10){
 78             countingSort(numbers, exp);
 79         }
 80     }
 81 
 82     /**
 83      * @Author: xingrui
 84      * @Description: 计数排序（纯数字）
 85      * @Date: 13:57 2019/1/30
 86      */
 87     private static void countingSort(int[] numbers, int exp){
 88         int n = numbers.length;
 89 
 90         int[] r = new int[n];
 91         int[] c = new int[10];
 92 
 93         for(int i = 0; i < n; ++i){
 94             c[numbers[i]/exp % 10]++;
 95         }
 96 
 97         for(int i = 1; i < 10; ++i){
 98             c[i] = c[i-1] + c[i];
 99         }
100 
101         for (int i = n - 1; i >= 0; --i){
102             int index = c[numbers[i] / exp % 10];
103             r[index - 1] = numbers[i];
104             c[numbers[i] / exp % 10]--;
105         }
106 
107         for(int i = 0; i < n; ++i){
108             numbers[i] = r[i];
109         }
110     }
111 
112     /**
113      * @Author: xingrui
114      * @Description: 自动补全单词
115      * @Date: 16:38 2019/1/30
116      */
117     private static void autoComplete(String[] words, int maxLength){
118         int i = 0;
119         for (String word : words) {
120             if(word.length() < maxLength){
121                 int value = maxLength - word.length();
122                 StringBuilder sb = new StringBuilder();
123                 for(int j = 0; j < value; ++j){
124                     sb.append("0");
125                 }
126                 words[i] = word + sb;
127             }
128             i++;
129         }
130     }
131 
132     /**
133      * @Author: xingrui
134      * @Description: 获取字符串最大的长度
135      * @Date: 15:56 2019/1/30
136      */
137     private static int getMaxLength(String[] words){
138         int maxLength = words[0].length();
139         for(int i = 1; i < words.length; ++i){
140             if(words[i].length() > maxLength)
141                 maxLength = words[i].length();
142         }
143         return maxLength;
144     }
145 
146     /**
147      * @Author: xingrui
148      * @Description: 获取最大的数字
149      * @Date: 15:56 2019/1/30
150      */
151     private static int getMaxNumber(int[] numbers){
152         int maxNumber = numbers[0];
153         for(int i = 1; i < numbers.length; ++i){
154             if(numbers[i] > maxNumber)
155                 maxNumber = numbers[i];
156         }
157         return maxNumber;
158     }
159 
160 }