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jackzhenguojackzhenguo
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tree tag more than 10 questions solution
1 parent 7958195 commit 5e1c83b

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+385
-15
lines changed

‎Tree/Tree.TreeLib/BanlancedTree.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace Tree.TreeLib
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{
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public class BanlancedTree
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{
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public bool IsBalanced(TreeNode root)
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{
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if (root == null)
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return true;
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if (Math.Abs(root.left.Height - root.right.Height) > 1)
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return false;
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return IsBalanced(root.left) && IsBalanced(root.right);
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}
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}
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}

‎Tree/Tree.TreeLib/CommonAncester.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace Tree.TreeLib
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{
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public class CommonAncester
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{
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public TreeNode LowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q)
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{
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if (root == null)
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return null;
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if (p == root || q == root) //等于root，则最小祖先一定为root
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return root;
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bool pOnLeft = isOn(root.left, p);
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bool qOnLeft = isOn(root.left, q);
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if (pOnLeft != qOnLeft)
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return root;
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if (pOnLeft == true && qOnLeft == true)
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return LowestCommonAncestor(root.left, p, q);
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return LowestCommonAncestor(root.right, p, q);
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}
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//位于node上吗
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private bool isOn(TreeNode node, TreeNode goal)
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{
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if (goal == null)
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return true;
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if (node == null)
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return false;
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if (node == goal)
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return true;
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if (isOn(node.left, goal) == true || isOn(node.right, goal) == true)
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return true;
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return false;
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}
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}
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}

‎Tree/Tree.TreeLib/DiameterTree.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace Tree.TreeLib
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{
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public class DiameterTree
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{
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public int DiameterOfBinaryTree(TreeNode root)
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{
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if (root == null)
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return 0;
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int max = Math.Max(nodeDiameter(root), DiameterOfBinaryTree(root.left));
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return Math.Max(max, DiameterOfBinaryTree(root.right));
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}
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private int nodeDiameter(TreeNode node)
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{
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if (node == null)
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return 0;
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int sum=0;
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if (node.left != null)
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sum += node.left.Height;
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if (node.right != null)
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sum += node.right.Height;
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return sum;
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}
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}
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}
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‎Tree/Tree.TreeLib/InvertTree.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace Tree.TreeLib
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{
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// Invert a binary tree.
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// 4
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// / \
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// 2 7
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// / \ / \
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//1 3 6 9
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//to
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// 4
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// / \
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// 7 2
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// / \ / \
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//9 6 3 1
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public class InvertTree
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{
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public TreeNode Invert(TreeNode root)
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{
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if (root == null)
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return null;
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var tmp = root.left;
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root.left = root.right;
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root.right = tmp;
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Invert(root.left);
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Invert(root.right);
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return root;
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}
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}
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}

‎Tree/Tree.TreeLib/LeftLeafSum.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace Tree.TreeLib
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{
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public class LeftLeafSum
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{
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public int SumOfLeftLeaves(TreeNode root)
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{
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if (root == null)
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return 0;
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int sum=0;
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if (root.left!=null && root.isLeaf())//左叶子
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sum += root.left.val;
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sum += SumOfLeftLeaves(root.left);
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sum += SumOfLeftLeaves(root.right);
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return sum;
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}
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}
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}

‎Tree/Tree.TreeLib/MaxMinDepth.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace Tree.TreeLib
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{
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public class MaxMinDepth
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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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return Math.Max(MaxDepth(root.left), MaxDepth(root.right)) + 1;
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}
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public int MinDepth(TreeNode root)
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{
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if (root == null)
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return 0;
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return Math.Min(MinDepth(root.left), MinDepth(root.right)) + 1;
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}
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}
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}

‎Tree/Tree.TreeLib/OnePathSum.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace Tree.TreeLib
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{
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//Given a binary tree and a sum, determine if the tree has a root-to-leaf path
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//such that adding up all the values along the path equals the given sum.
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public class OnePathSum
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{
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public bool HasPathSum(TreeNode root, int sum)
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{
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if (root == null)
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return false;
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if (root.val == sum && root.isLeaf()) //判断是否加到了叶子
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return true;
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//求以root为根的路径val和等于sum的
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if (HasPathSum(root.left, sum - root.val) == true)
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return true;
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return HasPathSum(root.right, sum - root.val);
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}
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}
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}

‎Tree/Tree.TreeLib/SortArrayToBalanced.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace Tree.TreeLib
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{
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public class SortArrayToBalanced
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{
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//Given an array where elements are sorted in ascending order, convert it to a height balanced BST.
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//nums = [1 2 3 4 5]
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public TreeNode SortedArrayToBST(int[] nums)
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{
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if (nums.Length == 0)
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return null;
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return subTree(nums, 0, nums.Length-1);
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}
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private TreeNode subTree(int[] nums, int begin, int end)
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{
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if (begin > end)
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return null;
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int mid = begin + (end - begin) / 2;
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TreeNode root = new TreeNode(nums[mid]);
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root.left = subTree(nums, begin, mid-1);
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root.right = subTree(nums, mid + 1, end);
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return root;
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}
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}
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}

‎Tree/Tree.TreeLib/SymmetricTree .cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace Tree.TreeLib
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{
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public class SymmetricTree
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{
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public bool IsSymmetric(TreeNode root)
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{
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if (root == null)
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return true;
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if (root.left == null && root.right == null)
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return true;
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if (root.left == null || root.right == null)
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return false;
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if (root.left.val != root.right.val)
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return false;
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TreeNode invertRight=invertTree(root.right);
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return isSameTree(root.left, invertRight);
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}
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//反转
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private TreeNode invertTree(TreeNode root)
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{
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if (root == null)
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return null;
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var tmp = root.left;
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root.left = root.right;
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root.right = tmp;
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invertTree(root.left);
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invertTree(root.right);
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return root;
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}
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//比较树是否相等
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private bool isSameTree(TreeNode p, TreeNode q)
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{
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if (p == null && q == null) return true;
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if (p == null || q == null) return false;
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return p.val == q.val &&
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isSameTree(p.left, q.left) &&
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isSameTree(p.right, q.right);
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}
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}
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}

‎Tree/Tree.TreeLib/Tree.TreeLib.csproj

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<Reference Include="System.Xml" />
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</ItemGroup>
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<ItemGroup>
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<Compile Include="BanlancedTree.cs" />
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<Compile Include="CommonAncester.cs" />
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<Compile Include="DiameterTree.cs" />
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<Compile Include="FindModes.cs" />
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<Compile Include="InvertTree.cs" />
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<Compile Include="LeftLeafSum.cs" />
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<Compile Include="MaxMinDepth.cs" />
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<Compile Include="OnePathSum.cs" />
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<Compile Include="SortArrayToBalanced.cs" />
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<Compile Include="SymmetricTree .cs" />
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<Compile Include="TreePaths.cs" />
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<Compile Include="LevelOrderTraversal.cs" />
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<Compile Include="Properties\AssemblyInfo.cs" />
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<Compile Include="SameTree.cs" />
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<Compile Include="TreeNode.cs" />
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<Compile Include="TreePathSum.cs" />
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<Compile Include="TreeTools.cs" />
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</ItemGroup>
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<ItemGroup>
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<Content Include="leetcode-tree.xml" />
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</ItemGroup>
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<Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
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<!-- To modify your build process, add your task inside one of the targets below and uncomment it.
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Other similar extension points exist, see Microsoft.Common.targets.

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