http://poj.grids.cn/problem?id=2692
利用枚舉，從'A'到'L'。判斷條件是：如果是'even'，則天平兩邊無假幣；如果是'up'，若為light，則假幣一定在天平右側(cè)，若為heavy，則假幣一定在天平左側(cè)；如果是'down'，情況相反。
1 #include<stdio.h>
2 #include<string.h>
3 #include<stdlib.h>
4 char left[3][7],right[3][7],result[3][5];
5 bool isLight(char c);
6 bool isheavy(char c);
7 int main()
8 {
9 int n;
10 while(scanf("%d",&n) != EOF){
11 while(n--){
12 for(int i = 0;i < 3;i++)
13 scanf("%s%s%s",left[i],right[i],result[i]);
14 char x;
15 for(x = 'A';x <= 'L';x++){
16 if(isLight(x)){
17 printf("%c is the counterfeit coin and it is light.\n",x);
18 break;
19 }
20 if(isheavy(x)){
21 printf("%c is the counterfeit coin and it is heavy.\n",x);
22 break;
23 }
24 }
25 }
26 }
27 system("pause");
28 return 0;
29 }
30
31 bool isLight(char c)
32 {
33 for(int i = 0;i < 3;i++){
34 if(!strcmp(result[i],"even"))
35 if(strchr(left[i],c) != NULL || strchr(right[i],c) != NULL)return false;
36 if(!strcmp(result[i],"up"))
37 if(strchr(right[i],c) == NULL)return false;
38 if(!strcmp(result[i],"down"))
39 if(strchr(left[i],c) == NULL)return false;
40 }
41 return true;
42 }
43
44 bool isheavy(char c)
45 {
46 for(int i = 0;i < 3;i++){
47 if(!strcmp(result[i],"even"))
48 if(strchr(left[i],c) != NULL || strchr(right[i],c) != NULL)return false;
49 if(!strcmp(result[i],"up"))
50 if(strchr(left[i],c) == NULL)return false;
51 if(!strcmp(result[i],"down"))
52 if(strchr(right[i],c) == NULL)return false;
53 }
54 return true;
55 }
56