Implement strStr().

Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

Example 1:

Input: haystack = "hello", needle = "ll"
Output: 2

Example 2:

Input: haystack = "aaaaa", needle = "bba"
Output: -1

Clarification:

What should we return when needle is an empty string? This is a great question to ask during an interview.

For the purpose of this problem, we will return 0 when needle is an empty string. This is consistent to C's strstr() and Java's indexOf().
 

应该用KMP，但是没用KMP好像也过去了。。。。。

int strStr(char * haystack, char * needle){
    int i = 0,j =0,t=i;//一定要有t
    while (haystack[i]&&needle[j]){
        if (haystack[i] == needle[j]){
            i++;
            j++;
            continue;
            //C 语言中的 continue 语句有点像 break 语句。但它不是强制终止，continue 会跳过当前循环中的代码，强迫开始下一次循环。
        } else{
            t=t+1;
            i=t;
            j=0;
        }
    }
    //如果needle串到了结尾的时候,代表顺利找到
    if (needle[j] == '\0'){
        return t;
    }
    //否则返回-1，没找到
    return -1;
}