Problem
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.
Returns 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().
What if both haystack and needle are empty?
Examples
Example 1:
Input: haystack = "hello", needle = "ll"
Output: 2
Example 2:
Input: haystack = "aaaaa", needle = "bba"
Output: -1
Solution
Here are all the methods. We will use the signature:
public class Solution {
public int strStr(String haystack, String needle) {
}
}
Method 1 - Naive
- Naive Brute Force String Search Algorithm
- If pattern has all distinct chars - Optimized Brute Force String Search Algorithm
Method 2 - Rabin Karp Algorithm
Rabin-Karp Algorithm Explained
Method 3 - Morris Pratt
Method 4 - Knuth Morris Pratt
Knuth Morris Pratt KMP Algorithm
Method 5 - Boyer Moore Algo
Method 6 - Z algo
Method. 7 - Using Suffix tree
[[4.data-structure-based-string-search]]
Parse the expression as tree Pattern Matching - Regular expression, deterministic and non-deterministic finite automaton (DFA and NFA)