1 /************************************************************************* 2 > File Name: test.c 3 > Author: ToLiMit 4 > Mail: 348958453@qq.com 5 > Created Time: Sun 04 Jan 2015 06:20:05 PM PST 6 ************************************************************************/ 7 8 #include<stdio.h> 9 10 void delete_str_char (char * main_str, char * sub_str) 11 { 12 if ((main_str == NULL) || (sub_str == NULL)) 13 return; 14 15 char * sub_index = sub_str; 16 char * main_index = main_str; 17 char bitmap[32] = {0}; 18 char * str = (char *)malloc (strlen (main_str) + 1); 19 char * index = str; 20 memset (str, 0, strlen (main_str) + 1); 21 22 while (*sub_index != ' ') { 23 char suffix = ((*sub_index) / 8) - 1; 24 char offset = (*sub_index) % 8; 25 26 bitmap[suffix] |= (0x1 << (8 - offset)); 27 sub_index++; 28 } 29 30 while (*main_index != ' ') { 31 char suffix = ((*main_index) / 8) - 1; 32 char offset = (*main_index) % 8; 33 34 if ((bitmap[suffix] & (0x1 << (8 - offset))) == 0) { 35 *index = *main_index; 36 index++; 37 } 38 main_index++; 39 } 40 41 *index = ' '; 42 memcpy (main_str, str, strlen (str) + 1); 43 free (str); 44 return; 45 } 46 47 int main (int argc, char * argv[]) 48 { 49 char test[] = "aabcdaaaaabcaacb"; 50 51 delete_str_char (test, "bcd"); 52 printf ("%s ", test); 53 return 0; 54 }
1. 用bitmap标记sub_str中出现过的字符
2. 申请一段buffer, 长度与main_str一致
3. 遍历main_str, 如果字符没有出现在bitmap中, 就将字符写入到buffer中
4. 遍历结束后, buffer中的数据就是删掉了sub_str中出现过的数据
时间复杂度: O(n + m) n为main_str长度, m为sub_str长度
空间复杂度: O(n)