Merge pull request gzc426#374 from sunny-ljc/master

gzc426 · web-flow · commit 9980e771de53 · 2018-12-08T11:42:35.000+08:00
Create Sunny.md
diff --git a/2018.12.06-leetcode103/Sunny.md b/2018.12.06-leetcode103/Sunny.md
@@ -0,0 +1,25 @@
+```java
+class Solution {
+    List<List<Integer>> result = new ArrayList<>();
+    public List<List<Integer>> zigzagLevelOrder(TreeNode root) {
+        zigzagLevelOrder(root, 0, false);
+        return result;
+    }
+    
+    public void zigzagLevelOrder(TreeNode node, int level, boolean inverse) {
+        if (node != null) {
+            if (result.size() <= level) {
+                result.add(new ArrayList<>());
+            }
+            if (inverse) {
+                result.get(level).add(0, node.val);
+            }
+            else {
+                result.get(level).add(node.val);
+            }
+            zigzagLevelOrder(node.left, level+1, !inverse);
+            zigzagLevelOrder(node.right, level+1, !inverse);
+        }
+    }
+}
+```
diff --git a/2018.12.07-leetcode104/Sunny.md b/2018.12.07-leetcode104/Sunny.md
@@ -0,0 +1,15 @@
+```java
+class Solution {
+    public int maxDepth(TreeNode root) {
+        if (root == null) return 0;
+        return Math.max(maxDepth(root.left, 1), maxDepth(root.right, 1));
+    }
+    
+    public int maxDepth(TreeNode node, int level) {
+        if (node != null) {
+            level = Math.max(maxDepth(node.left, level+1), maxDepth(node.right, level+1));
+        }
+        return level;
+    }
+}
+```
diff --git a/2018.12.08-leetcode105/Sunny.md b/2018.12.08-leetcode105/Sunny.md
@@ -0,0 +1,30 @@
+```java
+class Solution {
+
+    private int i = 0;
+    
+    public TreeNode buildTree(int[] preorder, int[] inorder) {
+        if (preorder == null || preorder.length == 0)
+            return null;
+        int val = preorder[i];
+        int index = inorder.length - 1;
+        for (; index >= 0; index--) {
+            if (inorder[index] == val) {
+                break;
+            }
+        }
+        if (index >= 0) {
+            TreeNode node = new TreeNode(val);
+            i++;
+            if (inorder.length > 1 && i < preorder.length) {
+                node.left = buildTree(preorder, Arrays.copyOfRange(inorder, 0, index));
+                if (i < preorder.length) {
+                    node.right = buildTree(preorder, Arrays.copyOfRange(inorder, index+1, inorder.length));
+                }
+            }
+            return node;
+        }
+        return null;
+    }
+}
+```
