Index of the First Occurrence in a String.cpp

class Solution {
public:
    int strStr(string haystack, string needle) {
        int haylength=haystack.length();
        int needlelength=needle.length();
        if(haylength<needlelength)
            return -1;
        for(int j=0;j<=haystack.size()-needle.size();j++){
            int i=0;
            while(i<needle.size() && haystack[i+j] == needle[i]){
                i++;
            }
            if(i == needle.size()){
                return j;
            }
        }
        return -1;
    }
};

/*
Given two strings needle and haystack, return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

 

Example 1:

Input: haystack = "sadbutsad", needle = "sad"
Output: 0
Explanation: "sad" occurs at index 0 and 6.
The first occurrence is at index 0, so we return 0.
Example 2:

Input: haystack = "leetcode", needle = "leeto"
Output: -1
Explanation: "leeto" did not occur in "leetcode", so we return -1.
 

Constraints:

1 <= haystack.length, needle.length <= 104
haystack and needle consist of only lowercase English characters.
*/