排序算法之计数排序

 1 /*
 2     用UVA 11462 Age Sort来验证算法的正确性
 3 */
 4 #include <cstdio>
 5 #include <cstring>
 6 #include <algorithm>
 7 #include <string>
 8 #include <cmath>
 9 #include <vector>
10 #include <map>
11 #include <set>
12 #include <cmath>
13 using namespace std;
14 
15 const int MAX_N = 2000000 + 10;
16 int a[MAX_N], w[MAX_N], p[MAX_N], o[MAX_N]; 
17 
18 void BucketSort(int *a, int n, int mx)
19 {
20     memset (w, 0, sizeof (w));
21     for (int i=1; i<=n; ++i)
22     {
23         w[a[i]]++;
24     }
25     for (int i=1; i<=mx; ++i)
26     {
27         w[i] += w[i-1];
28     }
29     for (int i=1; i<=n; ++i)
30     {
31         p[i] = w[a[i]];
32         w[a[i]]--;
33     }
34     for (int i=1; i<=n; ++i)
35     {
36         o[p[i]] = i;
37     }
38 }
39 
40 int main(void)        //UVA 11462 Age Sort
41 {
42     //freopen ("rand_small.in", "r", stdin);
43     int n;
44 
45     while (scanf ("%d", &n) != EOF && n)
46     {
47         int mx = 0;
48         for (int i=1; i<=n; ++i)
49         {
50             scanf ("%d", &a[i]);
51             if (a[i] > mx)
52             {
53                 mx = a[i];
54             }
55         }
56         BucketSort (a, n, mx);
57         
58         for (int i=1; i<=n; ++i)
59         {
60             printf ("%d%c", a[o[i]], (i==n) ? ‘\n‘ : ‘ ‘);
61         }
62     }
63     
64     return 0;
65 }

 1 /*
 2     用UVA 11462 Age Sort来验证算法的正确性
 3     我不知道它究竟是啥算法，计数，基数or桶排序？不过比上一个好的感觉:)
 4 */
 5 #include <cstdio>
 6 #include <algorithm>
 7 #include <cstring>
 8 using namespace std;
 9 
10 const int MAX_N = 2000000 + 10;
11 int a[MAX_N];
12 int num[MAX_N];
13 
14 void BucketSort(int *a, int p, int r)
15 {
16     for (int i=p; i<=r; ++i)
17     {
18         num[a[i]]++;
19     }
20 }
21 
22 int main(void)        //UVA 11462 Age Sort
23 {
24     freopen ("rand_small.in", "r", stdin);
25 
26     int n;
27     while (scanf ("%d", &n) != EOF && n)
28     {
29         memset (num, 0, sizeof (num));
30         int mx = -1;
31         for (int i=1; i<=n; ++i)
32         {
33             scanf ("%d", &a[i]);
34             if (a[i] > mx)    mx = a[i];
35         }
36      
37         BucketSort (a, 1, n);
38         
39         for (int i=0; i<=mx; ++i)
40         {
41             if (num[i] == 0)    continue;
42             else
43             {
44                 for (int j=1; j<=num[i]; ++j)
45                 {
46                     printf ("%d%c", i, (i==mx && j==num[i]) ? ‘\n‘ : ‘ ‘);
47                 }
48             }
49         }
50     }
51  
52     return 0;
53 }