Implement strStr()
题目:
mplement strStr().
Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
Update (2014-11-02):
The signature of the function had been updated to return the index instead of the pointer. If you still see your function signature returns a char * or String, please click the reload button to reset your code definition.
题意:
找到第二个字符串在第一个字符串中出现的下标,返回即可。
思路:
轮寻第一个字符串s1,比较s1的字符和s2的第一个字符,如果相等,则strncmp(s1, s2, len(s2)) == 0 ?。不相等则s1++。
class Solution {
public:
int strStr(string haystack, string needle) {
int len = needle.length();
if(len == 0){
return 0;
}
if(haystack.length() == 0){
return -1;
}
for(int i = 0; i < haystack.length(); ++i){
if(haystack[i] == needle[0] && haystack.substr(i, len) == needle){
return i;
}
}
return -1;
}
};