Being an interviewer - suggest char maximum occurrence given prefix - Julia learned to be an interviewer and compare the interviewee to herself.

SuggestCharMaximumOccurrenceGivenPrefix.cs

/*
Suppose you are supplied with a file containing a list of words like ABC,ACD, ABC 
( say each word in new line ). now you have to suggest algorithm for this problem - 
When a user type some character, we have to suggest him next character and basis of 
suggestion is that the character you are going to suggest should have maximum occurrence 
at that position with the given prefix. 

For example , Let's say words are 
ABC 
ACD
ABC
Now if user types 'A' we have to suggest him 'B' as next character with the prefix ‘A’, ‘B’ 
has 2 times, and ‘C’ has 1. similarly if he types 'AB' then we need to suggest him third 
character as 'C' as in third index since C has 2 times

Julia asked the interviewee to work on trie and put some numbers together before the interviewee wrote the code:

ABC 
ACD
ABC
A - Z -> 
        A 3
     /    \
    B  2      C 1
    /        \
   C 2         D 1
   
Advice Julia shared:
pramp.com - sharp your skills - structure your interview  
go through requirement -> missing anything? constraint
-> good communication
-> udemy.com   jeff bae - 14 dollars -> how much
pramp.com - free -> 
*/

using System;

class Solution
{
    static void Main(string[] args)
    {
        
        var sol=new Solution();
        var inputWords=new List<string>{"ABC","ACD","ABC"};
        var output=sol.
    }   
    
    public char FindNextSuggestion(List<string> words, string str){
        var trieRoot=new TrieNode();
        
        int index=0;
        foreach(var word in words){
            trieRoot.Add(word,index++);
        }
        
        var runner=trieRoot;
        foreach(char c in str){
            if(runner.Children[c-'A']==null)
                return '';
            runner=runner.Children[c-'A'];
        }
        
        TrieNode maxTrieNode=null
            
        for(var i=0;i<26;i++){
            if(runner.Children[i]==null)
                continue;
            
            if(maxTrieNode==null){
                maxTrieNode=runner.Children[i];   // orderIndex
                continue;
            }
            
            if(maxTrieNode.Count<runner.Children[i]){
                maxTrieNode=runner.Children[i];
            }
            else if(maxTrieNode.Count==runner.Children[i] && maxTrieNode.OrderIndex>runner.Children[i].OrderIndex){
                maxTrieNode=runner.Children[i];
            }
        }
        
        return maxTrieNode.Value;
    }
}

class TrieNode{
    public char Value{get;set;}
    public int Count{get;set;}'
    public int OrderIndex{get;set;}
    public TrieNode[] Children{get;set;}
    
    
    public TrieNode(char val,int index){
        this.Value=val;
        Children=new TrieNode[26]; 
        this.Count=1;
        this.OrderIndex=index;
    }
    
    public TrieNode(){
    }
    
    public void Add(string word,int index){
        var runner=root;
        foreach(char c in word){
            if(runner.Children[c-'A']==null){
                runner.Children[c-'A']=new TrieNode(c,index); //
                //runner.chi....OrderIndex = index; 
            }
            else{
                runner.Children[c-'A'].Count++;
            }
            
            runner=runner.Children[c-'A'];  //?
        }
    }
}