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Merge pull request gzc426#338 from PYTWSW/master
create WhiteNight.md
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‎2018.12.05-leetcode102/WhiteNight.md

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>```java
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>/**
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> * 二叉树的层次遍历1
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> * 给定一个二叉树，返回其按层次遍历的节点值。 （即逐层地，从左到右访问所有节点）。
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> *
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> */
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>public class Tree10
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>{
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> public static class TreeNode
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> {
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> int data;
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> TreeNode left;
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> TreeNode right;
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>
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> TreeNode(int val)
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> {
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> data = val;
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> }
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> }
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>
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> public List<List<Integer>> levelOrder(TreeNode root)
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> {
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> //JAVA泛型，List里面存储List，就可以有[[3], [9, 20], [15, 7]]
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> List<List<Integer>> list = new ArrayList<>();
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> List<Integer> temp = new ArrayList<>();
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>
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> Queue<TreeNode> queue = new LinkedList<>();
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>
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> if (root != null)
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> {
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> queue.offer(root);
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> }
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>
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> int width = 1;
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>
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> while (!queue.isEmpty())
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> {
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> TreeNode node = queue.poll();
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> temp.add(node.data);
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> width--;
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>
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> if (node.left != null)
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> queue.add(node.left);
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>
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> if (node.right != null)
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> queue.add(node.right);
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>
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> if (width == 0)
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> {
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> list.add(temp);
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> temp = new ArrayList<>();
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> width = queue.size();
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> }
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>
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> }
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>
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> return list;
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> }
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>
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> public static void main(String[] args)
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> {
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> TreeNode p = new TreeNode(3);
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> p.left = new TreeNode(9);
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> p.right = new TreeNode(20);
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> p.right.left = new TreeNode(15);
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> p.right.right = new TreeNode(7);
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>
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> Tree10 t = new Tree10();
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>
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> List<List<Integer>> list= t.levelOrder(p);
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> for (int i = 0; i < list.size(); i++)
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> {
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> System.out.print(list.get(i) + " ");
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> }
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>
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> }
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>
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>}
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>```
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‎2018.12.07-leetcode104/WhiteNight.md

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>```java
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>/**
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> * 给定一个二叉树，找出其最大深度。
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> *
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> * 二叉树的深度为根节点到最远叶子节点的最长路径上的节点数。
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> *
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> * 说明: 叶子节点是指没有子节点的节点。
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> *
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> */
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>public class Tree1
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>{
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> public static class TreeNode
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> {
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> int data;
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> TreeNode left;
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> TreeNode right;
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> TreeNode(int val)
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> {
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> data = val;
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> }
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> }
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>
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> public int maxDepth(TreeNode root)
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> {
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> if (root == null)
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> return 0;
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>
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> int nleft = maxDepth(root.left);
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> int nright = maxDepth(root.right);
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>
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> return nleft > nright ? nleft + 1 : nright + 1;
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> }
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>
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> public static void main(String[] args)
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> {
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> TreeNode p = new TreeNode(1);
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> p.left = new TreeNode(2);
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> p.right = new TreeNode(3);
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> p.left.left = null;
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> p.left.right = null;
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> p.right.left = new TreeNode(4);
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> p.right.right = new TreeNode(5);
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>
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> Tree1 t = new Tree1();
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> System.out.println(t.maxDepth(p));
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> }
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>}
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>```
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