《数据结构与算法分析：C语言描述》复习——第六章“排序”——基数排序

 1 // My implementation for radix sort.
 2 #include <algorithm>
 3 #include <iostream>
 4 #include <vector>
 5 using namespace std;
 6 
 7 void radixSort(vector<int> &v)
 8 {
 9     int n, i, j, k;
10     int max_val;
11     vector<vector<int> > rad;
12     
13     n = (int)v.size();
14     if (n <= 1) {
15         return;
16     }
17     
18     // This algorithm works for negative integers.
19     max_val = abs(v[0]);
20     for (i = 1; i < n; ++i) {
21         max_val = max(abs(v[i]), max_val);
22     }
23     
24     int exp = 1;
25     while (max_val / exp >= 10) {
26         exp *= 10;
27     }
28     
29     rad.resize(19);
30     int iexp = 1;
31     while (true) {
32         for (i = 0; i < n; ++i) {
33             rad[v[i] / iexp % 10 + 9].push_back(v[i]);
34         }
35         
36         k = 0;
37         for (i = 0; i < 19; ++i) {
38             int n2 = (int)rad[i].size();
39             for (j = 0; j < n2; ++j) {
40                 v[k++] = rad[i][j];
41             }
42             rad[i].clear();
43         }
44         
45         if (iexp == exp) {
46             break;
47         } else {
48             iexp *= 10;
49         }
50     }
51     rad.clear();
52 }
53 
54 int main()
55 {
56     vector<int> v;
57     int n, i;
58     
59     while (cin >> n && n > 0) {
60         v.resize(n);
61         for (i = 0; i < n; ++i) {
62             cin >> v[i];
63         }
64         radixSort(v);
65         for (i = 0; i < n; ++i) {
66             cout << v[i] << ‘ ‘;
67         }
68         cout << endl;
69     }
70     
71     return 0;
72 }