问题:
http://poj.org/problem?id=1016思路:
纯模拟，需要细心...
代码:
1 #include<stdio.h>
2 #include<stdlib.h>
3 #include<string.h>
4 #define NUM 10 /* 0..9 */
5 #define UP 15
6 #define INPUT_LEN 81
7 #define MAX_LEN 31
8 char input[INPUT_LEN], inv[UP][MAX_LEN];
9 int count[NUM];
10
11 void
12 generate(char *src, char *dst)
13 {
14 int i, index, len = strlen(src);
15 memset(count, 0, sizeof(count));
16 for(i=0; i<len; i++)
17 ++count[src[i]-'0'];
18
19 index = 0;
20 for(i=0; i<NUM; i++) {
21 if(count[i] > 0) {
22 if(count[i] >= 10) {
23 dst[index++] = (count[i]/10)+'0';
24 dst[index++] = (count[i]%10)+'0';
25 } else {
26 dst[index++] = count[i]+'0';
27 }
28 dst[index++] = i+'0';
29 }
30 }
31 }
32
33 void
34 solve()
35 {
36 int i, index = 0;
37 generate(input, inv[index]);
38 if(strcmp(input, inv[index]) == 0) {
39 printf("%s is self-inventorying\n", input);
40 return;
41 }
42 ++index;
43 while(index < UP) {
44 generate(inv[index-1], inv[index]);
45 if(strcmp(inv[index], inv[index-1]) == 0) {
46 printf("%s is self-inventorying after %d steps\n", input, index);
47 return;
48 }
49 for(i=index-2; i>=0; i--)
50 if(strcmp(inv[index], inv[i]) == 0) {
51 printf("%s enters an inventory loop of length %d\n", input, index-i);
52 return;
53 }
54 if(index >= 1)
55 if(strcmp(inv[index], input) == 0) {
56 printf("%s enters an inventory loop of length %d\n", input, index+1);
57 return;
58 }
59 ++index;
60 }
61 printf("%s can not be classified after 15 iterations\n", input);
62 }
63
64 int
65 main(int argc, char **argv)
66 {
67 while(scanf("%s", input) != EOF) {
68 if(strcmp(input, "-1") == 0)
69 break;
70 memset(inv, 0, sizeof(inv));
71 solve();
72 }
73 }