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 // 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”). 2 #include 
     
       3 #include 
      
        4 using namespace std; 5  6 class Solution { 7 public: 8     bool isStringRotation(char *s1, char *s2) { 9         if (s1 == nullptr || s2 == nullptr) {10             return false;11         }12         13         int len1, len2;14         15         len1 = strlen(s1);16         len2 = strlen(s2);17         if (len1 != len2) {18             return false;19         }20         21         const int MAXLEN = 1005;22         static char tmp[MAXLEN];23         24         tmp[0] = 0;25         strcat(tmp, s1);26         strcat(tmp, s1);27         return strstr(tmp, s2) != nullptr;28     }29 private:30     bool isSubstring(char *haystack, char *needle) {31         if (haystack == nullptr || needle == nullptr) {32             return false;33         }34         35         return strstr(haystack, needle) != nullptr;36     }37 };38 39 int main()40 {41     char s1[1005];42     char s2[1005];43     Solution sol;44     45     while (scanf("%s%s", s1, s2) == 2) {46         printf("\"%s\" is ", s2);47         if (!sol.isStringRotation(s1, s2)) {48             printf("not ");49         }50         printf("a rotation of \"%s\".\n", s1);51     }52     53     return 0;54 }