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Merge pull request #2361 from eeee0717/master

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Update0108.将有序数组转换为二叉搜索树，添加C#
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程序员Carl
2023-12-14 10:43:30 +08:00
committed by GitHub
parent f4ad5eca69 dcc37da603
commit cc8d122199
6 changed files with 239 additions and 2 deletions
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32
problems/0017.电话号码的字母组合.md
View File

@ -732,6 +732,38 @@ def backtracking(result, letter_map, digits, path, index)
end
end
```
### C#
```C#
public class Solution
{
public IList<string> res = new List<string>();
public string s;
public string[] letterMap = new string[10] { "", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz" };
public IList<string> LetterCombinations(string digits)
{
if (digits.Length == 0)
return res;
BackTracking(digits, 0);
return res;
}
public void BackTracking(string digits, int index)
{
if (index == digits.Length)
{
res.Add(s);
return;
}
int digit = digits[index] - '0';
string letters = letterMap[digit];
for (int i = 0; i < letters.Length; i++)
{
s += letters[i];
BackTracking(digits, index + 1);
s = s.Substring(0, s.Length - 1);
}
}
}
```
<p align="center">
<a href="https://programmercarl.com/other/kstar.html" target="_blank">

60
problems/0039.组合总和.md
View File

@ -598,6 +598,66 @@ object Solution {
}
}
```
### C#
```csharp
public class Solution
{
public IList<IList<int>> res = new List<IList<int>>();
public IList<int> path = new List<int>();
public IList<IList<int>> CombinationSum(int[] candidates, int target)
{
BackTracking(candidates, target, 0, 0);
return res;
}
public void BackTracking(int[] candidates, int target, int start, int sum)
{
if (sum > target) return;
if (sum == target)
{
res.Add(new List<int>(path));
return;
}
for (int i = start; i < candidates.Length; i++)
{
sum += candidates[i];
path.Add(candidates[i]);
BackTracking(candidates, target, i, sum);
sum -= candidates[i];
path.RemoveAt(path.Count - 1);
}
}
}
// 剪枝优化
public class Solution
{
public IList<IList<int>> res = new List<IList<int>>();
public IList<int> path = new List<int>();
public IList<IList<int>> CombinationSum(int[] candidates, int target)
{
Array.Sort(candidates);
BackTracking(candidates, target, 0, 0);
return res;
}
public void BackTracking(int[] candidates, int target, int start, int sum)
{
if (sum > target) return;
if (sum == target)
{
res.Add(new List<int>(path));
return;
}
for (int i = start; i < candidates.Length && sum + candidates[i] <= target; i++)
{
sum += candidates[i];
path.Add(candidates[i]);
BackTracking(candidates, target, i, sum);
sum -= candidates[i];
path.RemoveAt(path.Count - 1);
}
}
}
```
<p align="center">

54
problems/0077.组合.md
View File

@ -792,7 +792,59 @@ def backtracking(result, path, n, j, k)
end
```
### C#
```C#
// 暴力
public class Solution
{
public IList<IList<int>> res = new List<IList<int>>();
public IList<int> path = new List<int>();
public IList<IList<int>> Combine(int n, int k)
{
BackTracking(n, k, 1);
return res;
}
public void BackTracking(int n, int k, int start)
{
if (path.Count == k)
{
res.Add(new List<int>(path));
return;
}
for (int i = start; i <= n; i++)
{
path.Add(i);
BackTracking(n, k, i + 1);
path.RemoveAt(path.Count - 1);
}
}
}
// 剪枝
public class Solution
{
public IList<IList<int>> res = new List<IList<int>>();
public IList<int> path = new List<int>();
public IList<IList<int>> Combine(int n, int k)
{
BackTracking(n, k, 1);
return res;
}
public void BackTracking(int n, int k, int start)
{
if (path.Count == k)
{
res.Add(new List<int>(path));
return;
}
for (int i = start; i <= n - (k - path.Count) + 1; i++)
{
path.Add(i);
BackTracking(n, k, i + 1);
path.RemoveAt(path.Count - 1);
}
}
}
```
<p align="center">
<a href="https://programmercarl.com/other/kstar.html" target="_blank">
<img src="../pics/网站星球宣传海报.jpg" width="1000"/>

17
problems/0108.将有序数组转换为二叉搜索树.md
View File

@ -530,6 +530,23 @@ impl Solution {
}
}
```
### C#
```csharp
// 递归
public TreeNode SortedArrayToBST(int[] nums)
{
return Traversal(nums, 0, nums.Length - 1);
}
public TreeNode Traversal(int[] nums, int left, int right)
{
if (left > right) return null;
int mid = left + (right - left) / 2;
TreeNode node = new TreeNode(nums[mid]);
node.left = Traversal(nums, left, mid - 1);
node.right = Traversal(nums, mid + 1, right);
return node;
}
```
<p align="center">

61
problems/0216.组合总和III.md
View File

@ -633,7 +633,66 @@ object Solution {
}
}
```
### C#
```csharp
public class Solution
{
public IList<IList<int>> res = new List<IList<int>>();
public IList<int> path = new List<int>();
public IList<IList<int>> CombinationSum3(int k, int n)
{
BackTracking(k, n, 0, 1);
return res;
}
public void BackTracking(int k, int n, int sum, int start)
{
if (path.Count == k)
{
if (sum == n)
res.Add(new List<int>(path));
return;
}
for (int i = start; i <= 9; i++)
{
sum += i;
path.Add(i);
BackTracking(k, n, sum, i + 1);
sum -= i;
path.RemoveAt(path.Count - 1);
}
}
}
// 剪枝
public class Solution
{
public IList<IList<int>> res = new List<IList<int>>();
public IList<int> path = new List<int>();
public IList<IList<int>> CombinationSum3(int k, int n)
{
BackTracking(k, n, 0, 1);
return res;
}
public void BackTracking(int k, int n, int sum, int start)
{
if (sum > n)
return;
if (path.Count == k)
{
if (sum == n)
res.Add(new List<int>(path));
return;
}
for (int i = start; i <= 9 - (k - path.Count) + 1; i++)
{
sum += i;
path.Add(i);
BackTracking(k, n, sum, i + 1);
sum -= i;
path.RemoveAt(path.Count - 1);
}
}
}
```

17
problems/0538.把二叉搜索树转换为累加树.md
View File

@ -529,6 +529,23 @@ impl Solution {
}
}
```
### C#
```C#
// 递归
public class Solution
{
int pre = 0;
public TreeNode ConvertBST(TreeNode root)
{
if (root == null) return null;
ConvertBST(root.right);
root.val += pre;
pre = root.val;
ConvertBST(root.left);
return root;
}
}
```
<p align="center">