LeetCode28——Implement strStr()

Implement 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.

难度系数：

容易

实现

bool isSub(char *str, char *sub){    int len = strlen(sub);    for (int i = 0; i < len; ++i)    {        if (str[i] != sub[i])            return false;    }    return true;}int strStr(char *haystack, char * needle) {    int hlen = strlen(haystack);    int nlen = strlen(needle);    if (hlen == nlen && isSub(haystack, needle)) {        return 0;    }    for (int i = 0; i < hlen - nlen + 1; ++i) {        if (isSub(haystack+i, needle))            return i;    }    return -1;}