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package airbnb;

import java.util.LinkedList;
import java.util.List;
import java.util.Queue;



public class KEditDistance {

	public static void main(String[] args) {
		KEditDistance kEditDistance = new KEditDistance();
		TrieNode root = kEditDistance.new TrieNode();
		String[] lists = new String[] {"abcd", "abc", "abd","ad"};
		String word = "ac";
		int k = 1;
		List<String> result = kEditDistance.getKEditDistance(lists, word, k, root);
		for (String s : result) {
			System.out.println(s);
		}
	}
	
	public List<String> getKEditDistance(String[] lists, String target, int k, TrieNode root) {
		List<String> result = new LinkedList<>();
		if (lists == null || lists.length == 0 || target == null || target.length() == 0 || k < 0) {
			return result;
		}
		for (String s : lists) {
			root.add(s);
		}
		int[] prevDist = new int[target.length() + 1];
		for (int i = 0; i < prevDist.length; i++) {
			prevDist[i] = i;
		}
		
		computeDistance("", prevDist, target, k, root, result);
		return result;
	}
	
	public void computeDistance(String cur, int[] prevDist, String target, int k, TrieNode node, List<String> result) {
		if (node.isWord) {
			if (prevDist[target.length()] <= k) {
				result.add(cur);
			} else {
				return;
			}
		}

		for (int i = 0; i < 26; i++) {
			if (node.children[i] == null) {
				continue;
			}
//			print(node);

			int[] curDist = new int[target.length() + 1];
			curDist[0] = cur.length() + 1;
			for (int j = 1; j < prevDist.length; j++) {
				if (target.charAt(j - 1) == (char) (i + 'a')) {
					curDist[j] = prevDist[j - 1];
				} else {
					curDist[j] = Math.min(Math.min(prevDist[j - 1], prevDist[j]), curDist[j - 1]) + 1;
				}
			}
			
			computeDistance(cur + (char)(i + 'a'), curDist, target, k, node.children[i], result);
		}
	}
	
	public  void print(TrieNode root) {
		TrieNode cur = root;
		int level = 0;
		Queue<TrieNode> queue = new LinkedList<>();
		queue.add(cur);
		while (!queue.isEmpty()) {
			int size = queue.size();
			while (size > 0) {
				cur = queue.poll();
				System.out.println("level " + level + cur.character);
				for (int i = 0; i < cur.children.length; i++) {
					if (cur.children[i] != null) {
						queue.add(cur.children[i]);
					}
				}
				size--;
			}
			level++;
		}
		
	}
	
	class TrieNode {
		boolean isWord;
		TrieNode[] children;
		char character;
		
		public TrieNode() {
			children = new TrieNode[26];
		}
		
		public void add(String s) {
			if (s == null || s.length() == 0) {
				return;
			}
			TrieNode cur = this;
			for (int i = 0; i < s.length(); i++) {
				char c = s.charAt(i);
				if (cur.children[c - 'a'] == null) {
					cur.children[c - 'a'] = new TrieNode();
				}
				cur = cur.children[c - 'a'];
				cur.character = c;
			}
			cur.isWord = true;
		}
	}

}