Longest Common Prefix

LongestCommonPrefix.cs

/*
https://leetcode.com/problems/longest-common-prefix/

Write a function to find the longest common prefix string amongst an array of strings.

If there is no common prefix, return an empty string "".

 

Example 1:

Input: strs = ["flower","flow","flight"]
Output: "fl"

Example 2:

Input: strs = ["dog","racecar","car"]
Output: ""
Explanation: There is no common prefix among the input strings.

 

Constraints:

    1 <= strs.length <= 200
    0 <= strs[i].length <= 200
    strs[i] consists of only lower-case English letters.
*/

using System;

class Program 
{
	public static string LongestCommonPrefix(params string[] words) 
    {
		var firstWord = words[0];
		string commonPrefix = "";
		int arrayLength = words.Length;
		for(int i = 0, len = firstWord.Length; i < len; ++i)
		{
        	var prefixToCompare = firstWord.Substring(0, i + 1);
        	for(int j = 1; j < arrayLength; ++j)
        	{
            	if(words[j].IndexOf(prefixToCompare) == -1)
                	return commonPrefix;
        	}
			commonPrefix = prefixToCompare;
		}
        
        return commonPrefix;
    }
	public static void PrintResult(params string[] strs)
	{
		var result = LongestCommonPrefix(strs);
		if(result.Length == 0)
			Console.WriteLine("There is no common prefix among the input strings.");
		else
			Console.WriteLine($"Common Prefix: {result}");
	}
	
  	static void Main() 
  	{
		PrintResult("flower","flow","flight");  
		PrintResult("dog","racecar","car");
		PrintResult("mom", "mom", "mom", "mom");
		PrintResult("motherfuck", "mom", "mom", "mom");
		PrintResult("motherfuck", "body", "mom", "mom");
		PrintResult("motherfuck", "mom", "body", "mom");
		PrintResult("leets", "leetcode", "leet", "leeds");
  	}	
}