208-Implement-Trie.cs

public class TrieNode {
    public TrieNode() {
        childrenMap = new Dictionary<char, TrieNode>();
    }
    public Dictionary<char, TrieNode> childrenMap { get; set; }
    public bool isWord{ get; set; }
}
public class Trie {

    private TrieNode root;
    public Trie() {
        root = new TrieNode();
    }
    
    public void Insert(string word) {
        var cur = root;
        foreach(var c in word) {
            if(!cur.childrenMap.ContainsKey(c)) {
                cur.childrenMap[c] = new TrieNode();
            }
            cur = cur.childrenMap[c];
        }
        cur.isWord = true;
    }
    
    public bool Search(string word) {
        var node = traverse(word);
        return node != null && node.isWord;
    }
    
    public bool StartsWith(string prefix) {
        var node = traverse(prefix);
        return node!= null;
    }
    
    private TrieNode traverse(string path) {
        var cur = root;
        
        foreach(var c in path) {
            if(cur.childrenMap.ContainsKey(c)){
                cur = cur.childrenMap[c];
            }
            else {
                return null;
            }
        }
        return cur;
    }
}

/**
 * Your Trie object will be instantiated and called as such:
 * Trie obj = new Trie();
 * obj.Insert(word);
 * bool param_2 = obj.Search(word);
 * bool param_3 = obj.StartsWith(prefix);
 */