substring，

substring，

求a是否是b的字串问题

bool substring(char* ransomNote, char* magazine) {
    int rnum=strlen(ransomNote);
    int mnum=strlen(magazine);
    if(rnum>mnum)
        return false;
    else
    {
        char* cursor=magazine;
        char* tail=magazine+mnum-1;
        while(tail-cursor>=(rnum-1))
        {
            if(strncmp(cursor,ransomNote,rnum)==0)
            {
                return true;
            }
            ++cursor;
        }
        return false;
    }
}