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Commit 3334e5f

Browse files
Merge pull request youngyangyang04#2334 from eeee0717/master
Update.二叉树的递归遍历,添加C#版
2 parents 2a8c571 + 3ffca33 commit 3334e5f

7 files changed

+368
-19
lines changed

‎problems/0101.对称二叉树.md

Lines changed: 47 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -897,6 +897,53 @@ impl Solution {
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}
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}
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```
900+
### C#
901+
```C#
902+
// 递归
903+
public bool IsSymmetric(TreeNode root)
904+
{
905+
if (root == null) return true;
906+
return Compare(root.left, root.right);
907+
}
908+
public bool Compare(TreeNode left, TreeNode right)
909+
{
910+
if(left == null && right != null) return false;
911+
else if(left != null && right == null ) return false;
912+
else if(left == null && right == null) return true;
913+
else if(left.val != right.val) return false;
914+
915+
var outside = Compare(left.left, right.right);
916+
var inside = Compare(left.right, right.left);
917+
918+
return outside&&inside;
919+
}
920+
```
921+
``` C#
922+
// 迭代法
923+
public bool IsSymmetric(TreeNode root)
924+
{
925+
if (root == null) return true;
926+
var st = new Stack<TreeNode>();
927+
st.Push(root.left);
928+
st.Push(root.right);
929+
while (st.Count != 0)
930+
{
931+
var left = st.Pop();
932+
var right = st.Pop();
933+
if (left == null && right == null)
934+
continue;
935+
936+
if ((left == null || right == null || (left.val != right.val)))
937+
return false;
938+
939+
st.Push(left.left);
940+
st.Push(right.right);
941+
st.Push(left.right);
942+
st.Push(right.left);
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}
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return true;
945+
}
946+
```
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<p align="center">
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<a href="https://programmercarl.com/other/kstar.html" target="_blank">

‎problems/0102.二叉树的层序遍历.md

Lines changed: 51 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -462,6 +462,32 @@ impl Solution {
462462
}
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}
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```
465+
### C#
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```C#
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public IList<IList<int>> LevelOrder(TreeNode root)
468+
{
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var res = new List<IList<int>>();
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var que = new Queue<TreeNode>();
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if (root == null) return res;
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que.Enqueue(root);
473+
while (que.Count != 0)
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{
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var size = que.Count;
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var vec = new List<int>();
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for (int i = 0; i < size; i++)
478+
{
479+
var cur = que.Dequeue();
480+
vec.Add(cur.val);
481+
if (cur.left != null) que.Enqueue(cur.left);
482+
if (cur.right != null) que.Enqueue(cur.right);
483+
}
484+
res.Add(vec);
485+
486+
487+
}
488+
return res;
489+
}
490+
```
465491

466492

467493
**此时我们就掌握了二叉树的层序遍历了,那么如下九道力扣上的题目,只需要修改模板的两三行代码(不能再多了),便可打倒!**
@@ -798,6 +824,31 @@ impl Solution {
798824
}
799825
}
800826
```
827+
### C#
828+
```C#
829+
public IList<IList<int>> LevelOrderBottom(TreeNode root)
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{
831+
var res = new List<IList<int>>();
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var que = new Queue<TreeNode>();
833+
if (root == null) return res;
834+
que.Enqueue(root);
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while (que.Count != 0)
836+
{
837+
var size = que.Count;
838+
var vec = new List<int>();
839+
for (int i = 0; i < size; i++)
840+
{
841+
var cur = que.Dequeue();
842+
vec.Add(cur.val);
843+
if (cur.left != null) que.Enqueue(cur.left);
844+
if (cur.right != null) que.Enqueue(cur.right);
845+
}
846+
res.Add(vec);
847+
}
848+
res.Reverse();
849+
return res;
850+
}
851+
```
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## 199.二叉树的右视图
803854

‎problems/0104.二叉树的最大深度.md

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Original file line numberDiff line numberDiff line change
@@ -1022,6 +1022,61 @@ impl Solution {
10221022
max_depth
10231023
}
10241024
```
1025+
### C#
1026+
```C#
1027+
// 递归法
1028+
public int MaxDepth(TreeNode root) {
1029+
if(root == null) return 0;
1030+
1031+
int leftDepth = MaxDepth(root.left);
1032+
int rightDepth = MaxDepth(root.right);
1033+
1034+
return 1 + Math.Max(leftDepth, rightDepth);
1035+
}
1036+
```
1037+
```C#
1038+
// 前序遍历
1039+
int result = 0;
1040+
public int MaxDepth(TreeNode root)
1041+
{
1042+
if (root == null) return result;
1043+
GetDepth(root, 1);
1044+
return result;
1045+
}
1046+
public void GetDepth(TreeNode root, int depth)
1047+
{
1048+
result = depth > result ? depth : result;
1049+
if (root.left == null && root.right == null) return;
1050+
1051+
if (root.left != null)
1052+
GetDepth(root.left, depth + 1);
1053+
if (root.right != null)
1054+
GetDepth(root.right, depth + 1);
1055+
return;
1056+
}
1057+
```
1058+
```C#
1059+
// 迭代法
1060+
public int MaxDepth(TreeNode root)
1061+
{
1062+
int depth = 0;
1063+
Queue<TreeNode> que = new();
1064+
if (root == null) return depth;
1065+
que.Enqueue(root);
1066+
while (que.Count != 0)
1067+
{
1068+
int size = que.Count;
1069+
depth++;
1070+
for (int i = 0; i < size; i++)
1071+
{
1072+
var node = que.Dequeue();
1073+
if (node.left != null) que.Enqueue(node.left);
1074+
if (node.right != null) que.Enqueue(node.right);
1075+
}
1076+
}
1077+
return depth;
1078+
}
1079+
```
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<p align="center">
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<a href="https://programmercarl.com/other/kstar.html" target="_blank">

‎problems/0226.翻转二叉树.md

Lines changed: 7 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -1018,25 +1018,13 @@ public class Solution {
10181018
```csharp
10191019
//迭代
10201020
public class Solution {
1021-
public TreeNode InvertTree(TreeNode root) {
1022-
if (root == null) return null;
1023-
Stack<TreeNode> stack=new Stack<TreeNode>();
1024-
stack.Push(root);
1025-
while(stack.Count>0)
1026-
{
1027-
TreeNode node = stack.Pop();
1028-
swap(node);
1029-
if(node.right!=null) stack.Push(node.right);
1030-
if(node.left!=null) stack.Push(node.left);
1031-
}
1032-
return root;
1033-
}
1034-
1035-
public void swap(TreeNode node) {
1036-
TreeNode temp = node.left;
1037-
node.left = node.right;
1038-
node.right = temp;
1039-
}
1021+
public TreeNode InvertTree(TreeNode root) {
1022+
if(root == null) return root;
1023+
(root.left,root.right) = (root.right, root.left);
1024+
InvertTree(root.left);
1025+
InvertTree(root.right);
1026+
return root;
1027+
}
10401028
}
10411029
```
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‎problems/二叉树的统一迭代法.md

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Original file line numberDiff line numberDiff line change
@@ -741,6 +741,99 @@ impl Solution{
741741
}
742742
}
743743
```
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### C#
745+
```C#
746+
// 前序遍历
747+
public IList<int> PreorderTraversal(TreeNode root)
748+
{
749+
var res = new List<int>();
750+
var st = new Stack<TreeNode>();
751+
if (root == null) return res;
752+
st.Push(root);
753+
while (st.Count != 0)
754+
{
755+
var node = st.Peek();
756+
if (node == null)
757+
{
758+
st.Pop();
759+
node = st.Peek();
760+
st.Pop();
761+
res.Add(node.val);
762+
}
763+
else
764+
{
765+
st.Pop();
766+
if (node.right != null) st.Push(node.right);
767+
if (node.left != null) st.Push(node.left);
768+
st.Push(node);
769+
st.Push(null);
770+
}
771+
}
772+
return res;
773+
}
774+
```
775+
```C#
776+
// 中序遍历
777+
public IList<int> InorderTraversal(TreeNode root)
778+
{
779+
var res = new List<int>();
780+
var st = new Stack<TreeNode>();
781+
if (root == null) return res;
782+
st.Push(root);
783+
while (st.Count != 0)
784+
{
785+
var node = st.Peek();
786+
if (node == null)
787+
{
788+
st.Pop();
789+
node = st.Peek();
790+
st.Pop();
791+
res.Add(node.val);
792+
}
793+
else
794+
{
795+
st.Pop();
796+
if (node.right != null) st.Push(node.right);
797+
st.Push(node);
798+
st.Push(null);
799+
if (node.left != null) st.Push(node.left);
800+
}
801+
}
802+
return res;
803+
}
804+
```
805+
806+
```C#
807+
// 后序遍历
808+
public IList<int> PostorderTraversal(TreeNode root)
809+
{
810+
var res = new List<int>();
811+
var st = new Stack<TreeNode>();
812+
if (root == null) return res;
813+
st.Push(root);
814+
while (st.Count != 0)
815+
{
816+
var node = st.Peek();
817+
if (node == null)
818+
{
819+
st.Pop();
820+
node = st.Peek();
821+
st.Pop();
822+
res.Add(node.val);
823+
}
824+
else
825+
{
826+
st.Pop();
827+
if (node.left != null) st.Push(node.left);
828+
if (node.right != null) st.Push(node.right);
829+
st.Push(node);
830+
st.Push(null);
831+
}
832+
}
833+
res.Reverse(0, res.Count);
834+
return res;
835+
}
836+
```
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<p align="center">
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<a href="https://programmercarl.com/other/kstar.html" target="_blank">

‎problems/二叉树的迭代遍历.md

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Original file line numberDiff line numberDiff line change
@@ -695,6 +695,67 @@ impl Solution {
695695
}
696696
}
697697
```
698+
### C#
699+
```C#
700+
// 前序遍历
701+
public IList<int> PreorderTraversal(TreeNode root)
702+
{
703+
var st = new Stack<TreeNode>();
704+
var res = new List<int>();
705+
if (root == null) return res;
706+
st.Push(root);
707+
while (st.Count != 0)
708+
{
709+
var node = st.Pop();
710+
res.Add(node.val);
711+
if (node.right != null)
712+
st.Push(node.right);
713+
if (node.left != null)
714+
st.Push(node.left);
715+
}
716+
return res;
717+
}
718+
719+
// 中序遍历
720+
public IList<int> InorderTraversal(TreeNode root)
721+
{
722+
var st = new Stack<TreeNode>();
723+
var res = new List<int>();
724+
var cur = root;
725+
while (st.Count != 0 || cur != null)
726+
{
727+
if (cur != null)
728+
{
729+
st.Push(cur);
730+
cur = cur.left;
731+
}
732+
else
733+
{
734+
cur = st.Pop();
735+
res.Add(cur.val);
736+
cur = cur.right;
737+
}
738+
}
739+
return res;
740+
}
741+
// 后序遍历
742+
public IList<int> PostorderTraversal(TreeNode root)
743+
{
744+
var res = new List<int>();
745+
var st = new Stack<TreeNode>();
746+
if (root == null) return res;
747+
st.Push(root);
748+
while (st.Count != 0)
749+
{
750+
var cur = st.Pop();
751+
res.Add(cur.val);
752+
if (cur.left != null) st.Push(cur.left);
753+
if (cur.right != null) st.Push(cur.right);
754+
}
755+
res.Reverse(0, res.Count());
756+
return res;
757+
}
758+
```
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<p align="center">
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<a href="https://programmercarl.com/other/kstar.html" target="_blank">

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