[leetcode_28]Implement strStr()

I originally wanted to use KMP, but my getNext implementation was terrible and timed out.
I have been really exhausted lately. I will take a break for a while. I passed using naive pattern matching instead.
After some time I will practice again. For now I will read Kernighan and Ritchie’s “The C Programming Language” and “Computer Systems: A Programmer’s Perspective.” I am truly tired and under a lot of pressure.

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class Solution {
public:
    char *strStr(char *haystack, char *needle) {
        int lenh = strlen(haystack);
        int lenn = strlen(needle);
        if(lenh == 0 && lenn == 0)return haystack;
        for(int i = 0;i < lenh;i++) {
            if(strlen(haystack + i) >= lenn&&isEqual(haystack,i,needle))return haystack + i;
        }
        return NULL;
    }
private:
    bool isEqual(char *haystack,int i,char * needle) {
        int j;
        for(j = 0;j < strlen(needle);j++) {
            if(needle[j] != haystack[i+j])break;
        }
        if(j == strlen(needle))return true;
        else return false;
    }
};

KMP:

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class Solution {
public:
    int lenh;
    int lenn;
    int *next;
    char *strStr(char *haystack, char *needle) {
        lenh = strlen(haystack);
        lenn = strlen(needle);
        if(lenn == 0)return haystack;
        if(lenh < lenn)return NULL;
        next = new int[lenn];
        getNext(needle);
        int k = 0;
        int j = 0;
        while(j < lenh) {
            if(k == -1 || needle[k] == haystack[j]) {
                k++;
                j++;
                if(k == lenn)return haystack + j - lenn;
            }
            else 
                k = next[k];
        }
        return NULL;
    }
private:
    void getNext(char *needle) {
        int k = -1;
        int j = 0;
        next[j] = k;
        while(j < lenn-1) {
            if(k == -1 || needle[k] == needle[j]) {
                k++;
                j++;
                next[j] = k;
            }
            else
                k = next[k];
        }
    }
};