1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 char tab[65] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 5 
 6 int main()
 7 {
 8 
 9     //printf("%d %d %d %d\n", ‘M‘, ‘i‘, ‘k‘, ‘e‘);
10     int t, k;
11     unsigned char s[1024];
12     int i;
13     int len;
14     unsigned char a, b, c, d;
15     unsigned char s2[1024];
16     int cas = 0;
17     int j;
18     int tot;
19     //char
20 
21     scanf("%d", &t);
22 
23     while (t--) {
24         scanf("%d%s", &k, s);
25         len = strlen((const char *)s);
26         printf("Case #%d: ", ++cas);
27 
28         for (j = 0; j < k; ++j) {
29             tot = 0;
30             for (i = 0; i + 2 < len; i += 3) {
31                 a = s[i] >> 2;
32                 b = s[i] << 6, b >>= 2, b += s[i + 1] >> 4;
33                 c = s[i + 1] << 4, c >>= 2, c += s[i + 2] >> 6;
34                 d = s[i + 2] << 2, d >>= 2;
35                 //printf("%d %d %d %d\n", a, b, c, d);
36                 //printf("%c%c%c%c", tab[a], tab[b], tab[c], tab[d]);
37                 s2[tot++] = tab[a];
38                 s2[tot++] = tab[b];
39                 s2[tot++] = tab[c];
40                 s2[tot++] = tab[d];
41             }
42             if (i == len - 1) {
43                 a = s[i] >> 2;
44                 b = s[i] << 6, b >>= 2;
45                 //printf("%c%c==\n", tab[a], tab[b]);
46                 s2[tot++] = tab[a];
47                 s2[tot++] = tab[b];
48                 s2[tot++] = ‘=‘;
49                 s2[tot++] = ‘=‘;
50             } else if (i == len - 2) {
51                 a = s[i] >> 2;
52                 b = s[i] << 6, b >>= 2, b += s[i + 1] >> 4;
53                 c = s[i + 1] << 4, c >>= 2;
54                 //printf("%c%c%c=\n", tab[a], tab[b], tab[c]);
55                 s2[tot++] = tab[a];
56                 s2[tot++] = tab[b];
57                 s2[tot++] = tab[c];
58                 s2[tot++] = ‘=‘;
59             }
60             s2[tot] = ‘\0‘;
61             //printf("%s\n", s2);
62             strcpy((char *)s, (const char *)s2);
63             len = tot;
64             //printf("s = %s\n", s);
65         }
66         printf("%s\n", s2);
67     }
68 
69     return 0;
70 }