Day 5.1.txt

28. Implement strStr()

Implement strStr().

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
Example 3:

Input: haystack = "", needle = ""
Output: 0
 

Constraints:

0 <= haystack.length, needle.length <= 5 * 104
haystack and needle consist of only lower-case English characters.






class Solution {
    public int strStr(String h, String n) {
        if(n.length()>h.length())
                return -1;
        else if(n.length()==0)
            return 0;
        else
        {
            int i,c1=0;
            for(i=0;i<=h.length()-n.length();i++)
            {
                if(h.substring(i,i+n.length()).equals(n))
                {
                    return i;
                }
            }
            return -1;
        }
    }
}