Implement stsStr Leetcode solution

 28. Implement strStr()

Easy

Implement strStr().

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.

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().

 

Example 1:

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

Example 2:

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

 

Constraints:

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

Practice here:

(9) Implement strStr() - LeetCode

Solution :

class Solution {

public:

    int strStr(string haystack, string needle) {

        int i=0;

        int maxInd = haystack.length()-needle.length();

        while(i<=maxInd)

        {

            if(haystack[i]==needle[0])

            {

                int j=0;

                while(j<needle.length())

                {

                    if(needle[j]!=haystack[j+i])

                        break;

                    j++;

                }

                if(j==needle.length())

                    return i;

                

            }

            

            i++;

        }

        

        return -1;

    }

};