add 0500 and 0501 java version #255

Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,34 @@
	class Solution {

	public String[] findWords(String[] words) {
	if (words == null) {
	return null;
	}
	ArrayList<String> list = new ArrayList<>();
	String[] keyboards = {"qwertyuiop", "asdfghjkl", "zxcvbnm"};
	for (int i = 0; i < words.length; i++) {
	String word = words[i].toLowerCase();
	for (int j = 0; j < keyboards.length; j++) {
	// 先用word首字符确定属于哪一行
	if (keyboards[j].indexOf(word.charAt(0)) > -1) {
	// 判断word字符串所有字符是否都属于同一行
	boolean match = match(keyboards[j], word, list);
	if (match) {
	list.add(words[i]);
	}
	break;
	}
	}
	}
	return list.toArray(new String[list.size()]);
	}

	private boolean match(String keyboard, String word, ArrayList<String> list) {
	for (int i = 1; i < word.length(); i++) {
	if (keyboard.indexOf(word.charAt(i)) < 0) {
	return false;
	}
	}
	return true;
	}
	}

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Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,45 @@
	/**
	* Definition for a binary tree node.
	* public class TreeNode {
	* int val;
	* TreeNode left;
	* TreeNode right;
	* TreeNode(int x) { val = x; }
	* }
	*/
	class Solution {
	int max = 0;
	int cur = 0;
	TreeNode preNode = null;

	public int[] findMode(TreeNode root) {
	ArrayList<Integer> list = new ArrayList<>();
	findMode(root, list);
	int[] res = new int[list.size()];
	for (int i = 0; i < list.size(); i++) {
	res[i] = list.get(i);
	}
	return res;
	}

	private void findMode(TreeNode root, ArrayList<Integer> list) {
	if (root == null) {
	return;
	}
	findMode(root.left, list);
	if (preNode != null && root.val == preNode.val) {
	cur++;
	} else {
	cur = 1;
	}
	if (max < cur) {
	max = cur;
	list.clear();
	list.add(root.val);
	} else if (max == cur) {
	list.add(root.val);
	}
	preNode = root;
	findMode(root.right, list);
	}
	}

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