1 #include <stdio.h>
  2 #include <string.h>
  3 #include <stdlib.h>
  4 
  5 #define N 105
  6 #define WORD_MAX_SIZE 10
  7 
  8 char dictionary[N][WORD_MAX_SIZE];  // 字典
  9 int  dic_size;                      // 字典大小（字典中的word个数）
 10 
 11 char scrambled_word[WORD_MAX_SIZE]; // 待查找word
 12 
 13 char words[N][WORD_MAX_SIZE];   // 存放在字典中匹配查找到的单词
 14 int  words_num;                 // 纪录匹配的单词个数
 15 
 16 void permutation_check(char* p_str, char* p_begin);
 17 void swap(char* a, char* b);
 18 void search_in_dictionary(char str[]);
 19 void print();
 20 void del_newline_symbol(char* str);
 21 int cmp(const void* a, const void* b);
 22 
 23 int main()
 24 {
 25     int i = 0;
 26 
 27     // freopen("in.txt", "r", stdin);
 28 
 29     // load dictionary into memory
 30     while ( NULL != fgets(dictionary[i], WORD_MAX_SIZE, stdin) )
 31     {
 32         // 去掉读入的多余换行符
 33         del_newline_symbol(dictionary[i]);
 34 
 35         // load over
 36         if ( 0 == strcmp(dictionary[i], "XXXXXX") )
 37         {
 38             dic_size = i;
 39             break;
 40         }
 41         ++i;
 42     }
 43 
 44     while ( NULL != fgets(scrambled_word, WORD_MAX_SIZE, stdin) )
 45     {
 46         // 去掉读入的多余换行符
 47         del_newline_symbol(scrambled_word);
 48 
 49         // 检查结束
 50         if ( 0 == strcmp(scrambled_word, "XXXXXX") )
 51             break;
 52 
 53         // 初始化查找结果集合
 54         memset(words, 0, sizeof(words[0][0]) * N * WORD_MAX_SIZE);
 55         words_num = 0;
 56 
 57         // 对scrambled_word生成全排列，依次检查每一个排列
 58         permutation_check(scrambled_word, scrambled_word);
 59 
 60         // output 当前的scrambled_word的查找结果
 61         if ( 0 == words_num )
 62             printf("NOT A VALID WORD\n");
 63         else
 64             print();
 65         printf("******\n");
 66     }
 67     return 0;
 68 }
 69 
 70 void del_newline_symbol(char* str)
 71 {
 72     int len = strlen(str);
 73     if ( ‘\n‘ == str[len-1] )
 74         str[len-1] = ‘\0‘;
 75 }
 76 
 77 void print()
 78 {
 79     int i = 0;
 80     // 输出要求按照字典序递增，故先对words排序
 81     qsort(words, words_num, sizeof(words[0]), cmp);
 82 
 83     printf("%s\n", words[i]);
 84     for ( i = 1; i < words_num; ++i )
 85     {
 86         // 如果存在重复匹配，只输出一次
 87         if ( 0 != strcmp(words[i], words[i-1]) )
 88             printf("%s\n", words[i]);
 89     }
 90 }
 91 
 92 int cmp(const void* a, const void* b)
 93 {
 94     return strcmp((char *)a, (char *)b);
 95 }
 96 
 97 /*
 98  * core algorithm: Permutation全排列算法
 99  * */
100 void permutation_check(char* p_str, char* p_begin)
101 {
102     char * p_ch;
103     if ( ‘\0‘ == *p_begin )
104     {
105         search_in_dictionary(p_str);
106     }
107     else
108     {
109         for ( p_ch = p_begin; *p_ch != ‘\0‘; p_ch++ )
110         {
111             swap(p_begin, p_ch);
112             permutation_check(p_str, p_begin+1);
113             swap(p_begin, p_ch);
114         }
115     }
116 }
117 
118 void swap(char* a, char* b)
119 {
120     char t = *a;
121     *a = *b;
122     *b = t;
123 }
124 
125 void search_in_dictionary(char str[])
126 {
127     int i;
128     for ( i = 0; i < dic_size; ++i )
129     {
130         // 从字典中找到了，纪录下来
131         if ( 0 == strcmp(str, dictionary[i]) )
132         {
133             strncpy(words[words_num], str, WORD_MAX_SIZE);
134             ++words_num;
135         }
136     }
137 }