《Cracking the Coding Interview》——第1章：数组和字符串——题目8

2014-03-18 02:12

题目：判断一个字符串是否由另一个字符串循环移位而成。

解法：首先长度必须相等。然后将第一个串连拼两次，判断第二个串是否在这个连接串中。

代码：

 // 1.8 Assume you have a method isSubstring which checks if one word is a substring of another. Given two strings, s1 and s2, write code to check if s2 is a rotation of s1 using only one call to isSubstring (i.e., “waterbottle” is a rotation of “erbottlewat”).
 #include <cstdio>
 #include <cstring>
 using namespace std;

 class Solution {
 public:
     bool isStringRotation(char *s1, char *s2) {
         if (s1 == nullptr || s2 == nullptr) {
             return false;
         }

         int len1, len2;

         len1 = strlen(s1);
         len2 = strlen(s2);
         if (len1 != len2) {
             return false;
         }

         const int MAXLEN = ;
         static char tmp[MAXLEN];

         tmp[] = ;
         strcat(tmp, s1);
         strcat(tmp, s1);
         return strstr(tmp, s2) != nullptr;
     }
 private:
     bool isSubstring(char *haystack, char *needle) {
         if (haystack == nullptr || needle == nullptr) {
             return false;
         }

         return strstr(haystack, needle) != nullptr;
     }
 };

 int main()
 {
     char s1[];
     char s2[];
     Solution sol;

     while (scanf("%s%s", s1, s2) == ) {
         printf("\"%s\" is ", s2);
         if (!sol.isStringRotation(s1, s2)) {
             printf("not ");
         }
         printf("a rotation of \"%s\".\n", s1);
     }

     return ;
 }