Commit solution of leetcode 102 problem

xdu/passer/Java/passer_102.java

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+package com.passer._0320;
+/*
+	Problem:Binary Tree Level Order Traversal
+
+	Given a binary tree, return the level order traversal of its nodes' values.
+	(ie: from left to right, level by level).
+	For example:
+	Given binary tree
+	[3,9,20,null,null,15,7]
+    	3
+       / \
+      9  20
+         / \
+        15  7
+	return its level order traversal as:
+	[
+	 [3],
+	 [9,20],
+	 [15,7]
+	]
+*/
+
+import java.util.ArrayList;
+import java.util.List;
+
+class TreeNode {
+	int val;
+	TreeNode left;
+	TreeNode right;
+	TreeNode(int x) {
+		val = x;
+	}
+}
+
+public class Solution {
+	List<List<Integer>> listAll = new ArrayList<>();
+
+	public List<List<Integer>> levelOrder(TreeNode root) {
+		levelOrder(root, 0);
+		return listAll;
+	}
+
+	/**
+	* @param root	node of tree
+	* @param depth	depth of tree
+	 */
+	public void levelOrder(TreeNode root, int depth) {
+		if (root == null)
+			return;
+		List<Integer> list = null;
+		if (depth == listAll.size()) {
+			list = new ArrayList<>();
+			listAll.add(list);
+		} else {
+			list = listAll.get(depth);
+		}
+		list.add(root.val);
+		levelOrder(root.left, depth + 1);
+		levelOrder(root.right, depth + 1);
+	}
+}

xdu/passer/Java/passer_114.java

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+package com.passer._0321;
+
+/*
+Given a binary tree, flatten it to a linked list in-place.
+For example, given the following tree:
+    1
+   / \
+  2   5
+ / \   \
+3   4   6
+The flattened tree should look like:
+1
+ \
+  2
+   \
+    3
+     \
+      4
+       \
+        5
+         \
+          6
+*/
+public class Flatten {
+	public void flatten(TreeNode root) {
+		helper(root);
+	}
+
+	private TreeNode helper(TreeNode root) {
+		if (root == null)
+			return null;
+		TreeNode ans = helper(root.left);
+		root.left = helper(root.right);
+		root.right = ans;
+		ans = root;
+		while (ans.right != null) {
+			ans = ans.right;
+		}
+		ans.right = root.left;
+		root.left = null;
+		return root;
+	}
+}

xdu/passer/Java/passer_124.java

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+package com.passer._0321;
+
+class TreeNode {
+	int val;
+	TreeNode left;
+	TreeNode right;
+
+	TreeNode(int x) {
+		val = x;
+	}
+}
+
+public class MaxSumOfPath {
+    int maxValue;
+
+    public int maxPathSum(TreeNode root) {
+        maxValue = Integer.MIN_VALUE;
+        maxPathDown(root);
+        return maxValue;
+    }
+
+    private int maxPathDown(TreeNode node) {
+        if (node == null) return 0;
+        int left = Math.max(0, maxPathDown(node.left));
+        int right = Math.max(0, maxPathDown(node.right));
+        maxValue = Math.max(maxValue, left + right + node.val);
+        return Math.max(left, right) + node.val;
+    }
+}

xdu/passer/Java/passer_136.java

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+package com.passer._0321;
+
+/*Given a non-empty array of integers, every element appears twice except for one. Find that single one.
+
+	Note:
+
+	Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?
+
+	Example 1:
+
+	Input: [2,2,1]
+	Output: 1
+	Example 2:
+
+	Input: [4,1,2,1,2]
+	Output: 4
+*/
+public class SingleNum {
+	public int singleNumber(int[] nums) {
+		int ret = 0;
+		for (int i = 0; i < nums.length; i++) {
+			ret ^= nums[i];
+		}
+		return ret;
+	}
+}