leetCode 28. Implement strStr() 字符串

28. Implement strStr()

Implement strStr().

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

在haystack中找与needle 第一个相匹配的位置。如果找不到，返回-1。

代码如下：

class Solution {
public:
    int strStr(string haystack, string needle) {
        if(haystack.size() == 0 && needle.size() == 0)
            return 0;
        if(needle.size() == 0)
            return 0;
        if(haystack.size() < needle.size())
            return -1;
        for(int i = 0;i < haystack.size() - needle.size() + 1;i++)
        {
            bool flag = true;
            if(needle[0] == haystack[i])
            {
                int j = 0;
                for(; j < needle.size();j++)
                {
                    if(needle[j] != haystack[i+j])
                    {
                        flag = false;
                        break;
                    }
                        
                }
                if(flag)
                    return i;
            }
        }
        return -1;
    }
};

2016-08-11 01:02:49