mid = new ArrayList<>();
+ for (int i = 0; i < size; i++) {
+ TreeNode node = queue.poll();
+ mid.add(node.val);
+ if (node.left != null) {
+ queue.offer(node.left);
+ }
+ if (node.right != null) {
+ queue.offer(node.right);
+ }
+ }
+ result.add(mid);
+ }
+ return result;
+ }
+}
diff --git a/tree/No104.java b/tree/No104.java
new file mode 100644
index 0000000..56e8532
--- /dev/null
+++ b/tree/No104.java
@@ -0,0 +1,24 @@
+
+/**
+ * Definition for a binary tree node. public class TreeNode { int val; TreeNode
+ * left; TreeNode right; TreeNode(int x) { val = x; } }
+ */
+
+class TreeNodeInt {
+ int val;
+ TreeNodeInt left;
+ TreeNodeInt right;
+
+ TreeNodeInt(int x) {
+ val = x;
+ }
+}
+
+public class No104 {
+ public int maxDepth(TreeNodeInt root) {
+ if (root == null) {
+ return 0;
+ }
+ return 1 + Math.max(maxDepth(root.left), maxDepth(root.right));
+ }
+}
diff --git a/tree/No107.java b/tree/No107.java
new file mode 100644
index 0000000..485542e
--- /dev/null
+++ b/tree/No107.java
@@ -0,0 +1,47 @@
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+
+/**
+ * No107题解
+ *
+ * Created by tujietg on Jan 20, 2020
+ */
+public class No107 {
+
+ public List> levelOrderBottom(TreeNode root) {
+ Queue queue = new LinkedList();
+ List> result = new ArrayList>();
+
+ if (root == null) {
+ return result;
+ }
+ queue.add(root);
+ while (!queue.isEmpty()) {
+ int length = queue.size();
+ List midList = new ArrayList();
+ for (int i = 0; i < length; i++) {
+ if (queue.peek().left != null) {
+ queue.offer(queue.peek().left);
+ }
+ if (queue.peek().right != null) {
+ queue.offer(queue.peek().right);
+ }
+ midList.add(queue.poll().val);
+ }
+ result.add(0, midList);
+ }
+ return result;
+ }
+
+ public static void main(String[] args) {
+ TreeNode root = new TreeNode(3);
+ root.left = new TreeNode(9);
+ root.right = new TreeNode(20);
+ root.right.left = new TreeNode(15);
+ root.right.right = new TreeNode(7);
+ new No107().levelOrderBottom(root);
+ }
+
+}
diff --git a/tree/No108.java b/tree/No108.java
new file mode 100644
index 0000000..9e3245a
--- /dev/null
+++ b/tree/No108.java
@@ -0,0 +1,21 @@
+
+/**
+ * Created by tujietg on Nov 6, 2019
+ */
+class Solution {
+ public TreeNode sortedArrayToBST(int[] nums) {
+ return toBST(nums, 0, nums.length - 1);
+ }
+
+ // 方法对数组生成树 每个数组的中间值等于每个树或者子树的根节点
+ public static TreeNode toBST(int[] nums, int start, int end) {
+ if (start > end) {
+ return null;
+ }
+ int mid = (start + end) / 2;
+ TreeNode node = new TreeNode(nums[mid]);
+ node.left = toBST(nums, start, mid - 1);
+ node.right = toBST(nums, mid + 1, end);
+ return node;
+ }
+}
\ No newline at end of file
diff --git a/tree/No110.java b/tree/No110.java
new file mode 100644
index 0000000..d28862e
--- /dev/null
+++ b/tree/No110.java
@@ -0,0 +1,39 @@
+
+/**
+ * Created by tujietg on Nov 6, 2019
+ */
+public class No110 {
+ public static boolean isBalanced(TreeNode root) {
+ if (root == null)
+ return true;
+ int a = depth(root.left);
+ System.out.println(a);
+ int b = depth(root.right);
+ System.out.println(b);
+ return Math.abs(a - b) <= 1;
+ }
+
+ // 求出子树的高度
+ public static int depth(TreeNode root) {
+ if (root == null) {
+ return 0;
+ }
+ // 通过递归来求出每个子树的高度
+ return Math.max(depth(root.left), depth(root.right)) + 1;
+ }
+
+ // [1,2,2,3,null ,null,3, 4,null,null,4]
+ public static void main(String[] args) {
+ TreeNode root = new TreeNode(1);
+ root.left = new TreeNode(2);
+ root.right = new TreeNode(2);
+ root.left.left = new TreeNode(3);
+ root.left.right = null;
+ root.right.left = null;
+ root.right.right = new TreeNode(3);
+ root.left.left.left = new TreeNode(4);
+ root.right.right.right = new TreeNode(4);
+ System.out.println(isBalanced(root));
+ }
+
+}
diff --git a/tree/No111.java b/tree/No111.java
new file mode 100644
index 0000000..0a5d689
--- /dev/null
+++ b/tree/No111.java
@@ -0,0 +1,30 @@
+
+/**
+ * Created by tujietg on Nov 6, 2019
+ */
+public class No111 {
+
+ static int i = 0;
+
+ public static int minDepth(TreeNode root) {
+ if (root == null) {
+ return 0;
+ }
+
+ int left = minDepth(root.left);
+ int right = minDepth(root.right);
+ return (left == 0 || right == 0) ? left + right + 1 : Math.min(left + 1, right + 1);
+ }
+
+ // [3,9,20,null,null,15,7]
+ public static void main(String[] args) {
+ TreeNode root = new TreeNode(3);
+ root.left = new TreeNode(9);
+ root.right = new TreeNode(20);
+ root.left.left = null;
+ root.left.right = null;
+ root.right.left = new TreeNode(15);
+ root.right.right = new TreeNode(7);
+ System.out.println(minDepth(root));
+ }
+}
diff --git a/tree/No112.java b/tree/No112.java
new file mode 100644
index 0000000..90f1b73
--- /dev/null
+++ b/tree/No112.java
@@ -0,0 +1,15 @@
+
+/**
+ * Created by tujietg on Nov 6, 2019
+ */
+public class No112 {
+ public boolean hasPathSum(TreeNode root, int sum) {
+ if (root == null) {
+ return false;
+ }
+ if (root.left == null && root.right == null && sum - root.val == 0) {
+ return true;
+ }
+ return hasPathSum(root.left, sum - root.val) || hasPathSum(root.right, sum - root.val);
+ }
+}
diff --git a/tree/No1302.java b/tree/No1302.java
new file mode 100644
index 0000000..ff5ebff
--- /dev/null
+++ b/tree/No1302.java
@@ -0,0 +1,28 @@
+
+import java.util.LinkedList;
+import java.util.Queue;
+
+/**
+ * No1302
+ *
+ * Created by tujietg on Jan 20, 2020
+ */
+public class No1302 {
+ public int deepestLeavesSum(TreeNode root) {
+ int reslut = 0, i;
+ Queue queue = new LinkedList();
+ queue.add(root);
+ while (!queue.isEmpty()) {
+ int len = queue.size();
+ for (i = len - 1, reslut = 0; i >= 0; i--) {
+ TreeNode node = queue.poll();
+ reslut += node.val;
+ if (node.left != null)
+ queue.add(node.left);
+ if (node.right != null)
+ queue.add(node.right);
+ }
+ }
+ return reslut;
+ }
+}
diff --git a/tree/No1305.java b/tree/No1305.java
new file mode 100644
index 0000000..0546881
--- /dev/null
+++ b/tree/No1305.java
@@ -0,0 +1,30 @@
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * No1305
+ *
+ * Created by tujietg on Jan 23, 2020
+ */
+public class No1305 {
+ List list = new ArrayList();
+
+ public List getAllElements(TreeNode root1, TreeNode root2) {
+ addList(root1);
+ addList(root2);
+ Collections.sort(list);
+ return list;
+ }
+
+ public void addList(TreeNode node) {
+ if (node == null) {
+ return;
+ }
+ list.add(node.val);
+ addList(node.left);
+ addList(node.right);
+ }
+
+}
diff --git a/tree/No1315.java b/tree/No1315.java
new file mode 100644
index 0000000..4c3672e
--- /dev/null
+++ b/tree/No1315.java
@@ -0,0 +1,18 @@
+
+/**
+ * No1315
+ *
+ * Created by tujietg on Jan 20, 2020
+ */
+public class No1315 {
+ public int sumEvenGrandparent(TreeNode root) {
+ return helper(root, 1, 1);
+ }
+
+ public int helper(TreeNode node, int p, int gp) {
+ if (node == null) {
+ return 0;
+ }
+ return helper(node.left, node.val, p) + helper(node.right, node.val, p) + (gp % 2 == 0 ? node.val : 0);
+ }
+}
diff --git a/tree/No145.java b/tree/No145.java
new file mode 100644
index 0000000..d2aabbf
--- /dev/null
+++ b/tree/No145.java
@@ -0,0 +1,20 @@
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * No145 Created by tujietg on Feb 5, 2020
+ */
+public class No145 {
+ List result = new ArrayList();
+
+ public List postorderTraversal(TreeNode root) {
+ if (root == null) {
+ return result;
+ }
+ postorderTraversal(root.left);
+ postorderTraversal(root.right);
+ result.add(root.val);
+ return result;
+ }
+}
diff --git a/tree/No226.java b/tree/No226.java
new file mode 100644
index 0000000..31979e2
--- /dev/null
+++ b/tree/No226.java
@@ -0,0 +1,17 @@
+
+/**
+ * Created by tujietg on Nov 6, 2019
+ */
+public class No226 {
+ public TreeNode invertTree(TreeNode root) {
+ // 使用遍历交换左子树和右子树
+ if (root == null) {
+ return null;
+ }
+ TreeNode left = invertTree(root.left);
+ TreeNode right = invertTree(root.right);
+ root.left = right;
+ root.right = left;
+ return root;
+ }
+}
diff --git a/tree/No235.java b/tree/No235.java
new file mode 100644
index 0000000..a44beb7
--- /dev/null
+++ b/tree/No235.java
@@ -0,0 +1,14 @@
+/**
+ * Created by tujietg on Dec 15, 2019
+ */
+public class No235 {
+ public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
+ if (root.val > p.val && root.val > q.val) {
+ return lowestCommonAncestor(root.left, p, q);
+ } else if (root.val < q.val && root.val < p.val) {
+ return lowestCommonAncestor(root.right, p, q);
+ } else {
+ return root;
+ }
+ }
+}
diff --git a/tree/No257.java b/tree/No257.java
new file mode 100644
index 0000000..2cd6554
--- /dev/null
+++ b/tree/No257.java
@@ -0,0 +1,29 @@
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Created by tujietg on Dec 16, 2019
+ */
+public class No257 {
+ public List binaryTreePaths(TreeNode root) {
+ List endList = new ArrayList();
+ if (root != null) {
+ fun(root, "", endList);
+ }
+ return endList;
+ }
+
+ void fun(TreeNode root, String path, List endList) {
+ if (root.left == null && root.right == null) {
+ endList.add(path + root.val);
+ }
+ if (root.left != null) {
+ fun(root.left, path + root.val + "->", endList);
+ }
+
+ if (root.right != null) {
+ fun(root.right, path + root.val + "->", endList);
+ }
+ }
+}
diff --git a/tree/No404.java b/tree/No404.java
new file mode 100644
index 0000000..b8632aa
--- /dev/null
+++ b/tree/No404.java
@@ -0,0 +1,20 @@
+
+/**
+ * Created by tujietg on Jan 12, 2020
+ */
+public class No404 {
+ public int sumOfLeftLeaves(TreeNode root) {
+ if (root == null)
+ return 0;
+ int answer = 0;
+ if (root.left != null) {
+ if (root.left.left == null && root.left.right == null) {
+ answer += root.left.val;
+ } else {
+ answer += sumOfLeftLeaves(root.left);
+ }
+ }
+ answer += sumOfLeftLeaves(root.right);
+ return answer;
+ }
+}
diff --git a/tree/No559.java b/tree/No559.java
new file mode 100644
index 0000000..9518250
--- /dev/null
+++ b/tree/No559.java
@@ -0,0 +1,22 @@
+
+/**
+ * No559
+ *
+ * Created by tujietg on Jan 22, 2020
+ */
+public class No559 {
+ public int maxDepth(Node root) {
+ if (root == null) {
+ return 0;
+ }
+ int end = 0;
+ for (Node node : root.children) {
+ int value = maxDepth(node);
+
+ if (value > end) {
+ end = value;
+ }
+ }
+ return end + 1;
+ }
+}
diff --git a/tree/No589.java b/tree/No589.java
new file mode 100644
index 0000000..d8feca4
--- /dev/null
+++ b/tree/No589.java
@@ -0,0 +1,42 @@
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * No589
+ *
+ * Created by tujietg on Jan 21, 2020
+ */
+class Node {
+ public int val;
+ public List children;
+
+ public Node() {
+ }
+
+ public Node(int _val) {
+ val = _val;
+ }
+
+ public Node(int _val, List _children) {
+ val = _val;
+ children = _children;
+ }
+}
+
+public class No589 {
+
+ List list = new ArrayList();
+
+ public List preorder(Node root) {
+ if (root == null) {
+ return list;
+ }
+ list.add(root.val);
+ for (Node node : root.children) {
+ preorder(node);
+ }
+ return list;
+ }
+
+}
diff --git a/tree/No590.java b/tree/No590.java
new file mode 100644
index 0000000..747e46e
--- /dev/null
+++ b/tree/No590.java
@@ -0,0 +1,23 @@
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Created by tujietg on Jan 21, 2020
+ */
+public class No590 {
+
+ List list = new ArrayList();
+
+ public List preorder(Node root) {
+ if (root == null) {
+ return list;
+ }
+ for (Node node : root.children) {
+ preorder(node);
+ }
+ list.add(root.val);
+ return list;
+ }
+
+}
diff --git a/tree/No617.java b/tree/No617.java
new file mode 100644
index 0000000..a60648c
--- /dev/null
+++ b/tree/No617.java
@@ -0,0 +1,18 @@
+
+/**
+ * Created by tujietg on Nov 6, 2019
+ */
+public class No617 {
+ public TreeNode mergeTrees(TreeNode t1, TreeNode t2) {
+ if (t1 == null && t2 == null) {
+ return null;
+ }
+ int newval = (t1 == null ? 0 : t1.val) + (t2 == null ? 0 : t2.val);
+
+ TreeNode newtree = new TreeNode(newval);
+
+ newtree.left = mergeTrees(t1 == null ? null : t1.left, t2 == null ? null : t2.left);
+ newtree.right = mergeTrees(t1 == null ? null : t1.right, t2 == null ? null : t2.right);
+ return newtree;
+ }
+}
diff --git a/tree/No700.java b/tree/No700.java
new file mode 100644
index 0000000..f81b9ea
--- /dev/null
+++ b/tree/No700.java
@@ -0,0 +1,21 @@
+
+/**
+ * No700
+ *
+ * Created by tujietg on Jan 20, 2020
+ */
+public class No700 {
+ public TreeNode searchBST(TreeNode root, int val) {
+ if (root == null) {
+ return root;
+ }
+ if (root.val == val) {
+ return root;
+ } else if (root.val > val) {
+ return searchBST(root.left, val);
+ } else if (root.val < val) {
+ return searchBST(root.right, val);
+ }
+ return null;
+ }
+}
diff --git a/tree/No938.java b/tree/No938.java
new file mode 100644
index 0000000..118d89a
--- /dev/null
+++ b/tree/No938.java
@@ -0,0 +1,15 @@
+
+/**
+ * Created by tujietg on Jan 10, 2020
+ */
+public class No938 {
+ public int rangeSumBST(TreeNode root, int L, int R) {
+ if (root == null)
+ return 0;
+ if (root.val < L)
+ return rangeSumBST(root.right, L, R);
+ if (root.val > R)
+ return rangeSumBST(root.left, L, R);
+ return root.val + rangeSumBST(root.left, L, R) + rangeSumBST(root.right, L, R);
+ }
+}
diff --git a/tree/No94.java b/tree/No94.java
new file mode 100644
index 0000000..ac55fcf
--- /dev/null
+++ b/tree/No94.java
@@ -0,0 +1,24 @@
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * No94
+ *
+ * Created by tujietg on Jan 26, 2020
+ */
+public class No94 {
+ List list = new ArrayList<>();
+
+ public List inorderTraversal(TreeNode root) {
+ if (root == null) {
+ return list;
+ }
+ inorderTraversal(root.left);
+ list.add(root.val);
+ inorderTraversal(root.right);
+ return list;
+ }
+
+}
+
+
diff --git a/tree/No965.java b/tree/No965.java
new file mode 100644
index 0000000..015a2b4
--- /dev/null
+++ b/tree/No965.java
@@ -0,0 +1,21 @@
+
+/**
+ * No965
+ *
+ * Created by tujietg on Jan 21, 2020
+ */
+public class No965 {
+ public boolean isUnivalTree(TreeNode root) {
+ if (root == null) {
+ return true;
+ }
+ if (root.left != null && root.left.val != root.val) {
+ return false;
+ }
+ if (root.right != null && root.right.val != root.val) {
+ return false;
+ }
+
+ return isUnivalTree(root.left) && isUnivalTree(root.right);
+ }
+}
diff --git a/tree/Nom28.java b/tree/Nom28.java
new file mode 100644
index 0000000..65b9b15
--- /dev/null
+++ b/tree/Nom28.java
@@ -0,0 +1,25 @@
+package tree;
+
+/**
+ * @author tujietg
+ * @date 6/4/20 2:58 PM
+ */
+public class Nom28 {
+
+ public boolean isSymmetric(TreeNode root) {
+ if (root == null) {
+ return true;
+ }
+ return check(root.left, root.right);
+ }
+
+ boolean check(TreeNode rootLeft, TreeNode rootRight) {
+ if (rootLeft == null && rootRight == null) {
+ return true;
+ }
+ if (rootLeft == null || rootRight == null) {
+ return false;
+ }
+ return rootLeft.val == rootRight.val && check(rootLeft.left, rootRight.right) && check(rootLeft.right, rootRight.left);
+ }
+}
diff --git a/tree/Nom68.java b/tree/Nom68.java
new file mode 100644
index 0000000..ec7a054
--- /dev/null
+++ b/tree/Nom68.java
@@ -0,0 +1,24 @@
+package tree;
+
+/**
+ * @author tujietg
+ * @date 5/30/20 11:05 AM
+ */
+public class Nom68 {
+
+ public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
+ if (root == null || root == p || root == q) {
+ return root;
+ }
+ TreeNode leftNode = lowestCommonAncestor(root.left, p, q);
+ TreeNode rightNode = lowestCommonAncestor(root.right, p, q);
+ if (leftNode == null) {
+ return rightNode;
+ }
+ if (rightNode == null) {
+ return leftNode;
+ }
+ return root;
+ }
+
+}
diff --git a/tree/TreeNode.java b/tree/TreeNode.java
new file mode 100644
index 0000000..c8a32bc
--- /dev/null
+++ b/tree/TreeNode.java
@@ -0,0 +1,16 @@
+package tree;
+
+/**
+ * @author tujietg
+ * @date 5/30/20 11:06 AM
+ */
+public class TreeNode {
+
+ int val;
+ TreeNode left;
+ TreeNode right;
+
+ TreeNode(int x) {
+ val = x;
+ }
+}