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72
problems/0104.二叉树的最大深度.md
View File

@ -1033,6 +1033,9 @@ impl Solution {
}
```
### C#
0104.二叉树的最大深度
```csharp
// 递归法
public int MaxDepth(TreeNode root) {
@ -1088,7 +1091,76 @@ public int MaxDepth(TreeNode root)
}
```
559.n叉树的最大深度
递归法
```csharp
/*
递归法
*/
public class Solution {
public int MaxDepth(Node root) {
int res = 0;
/* 终止条件 */
if(root == null){
return 0;
}
/* logic */
// 遍历当前节点的子节点
for (int i = 0; i < root.children.Count; i++)
{
res = Math.Max(res, MaxDepth(root.children[i]));
}
return res + 1;
}
}
// @lc code=end
```
迭代法（层序遍历）
```csharp
/*
迭代法
*/
public class Solution
{
public int MaxDepth(Node root)
{
Queue<Node> que = new Queue<Node>(); // 使用泛型队列存储节点
int res = 0;
if(root != null){
que.Enqueue(root); // 将根节点加入队列
}
while (que.Count > 0)
{
int size = que.Count; // 获取当前层的节点数
res++; // 深度加一
for (int i = 0; i < size; i++)
{
// 每一层的遍历
var curNode = que.Dequeue(); // 取出队列中的节点
for (int j = 0; j < curNode.children.Count; j++)
{
if (curNode.children[j] != null)
{
que.Enqueue(curNode.children[j]); // 将子节点加入队列
}
}
}
}
return res; // 返回树的最大深度
}
}
```
<p align="center">
<a href="https://programmercarl.com/other/kstar.html" target="_blank">
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</a>

56
problems/0112.路径总和.md
View File

@ -1523,8 +1523,64 @@ public bool HasPathSum(TreeNode root, int targetSum)
return HasPathSum(root.left, targetSum - root.val) || HasPathSum(root.right, targetSum - root.val);
}
```
0113.路径总和：
```csharp
/*
* @lc app=leetcode id=113 lang=csharp
* 0113.路径总和 II
* [113] Path Sum II
* 递归法
*/
public class Solution {
private List<List<int>> result = new List<List<int>>();
private List<int> path = new List<int>();
// Main function to find paths with the given sum
public IList<IList<int>> PathSum(TreeNode root, int targetSum) {
result.Clear();
path.Clear();
if (root == null) return result.Select(list => list as IList<int>).ToList();
path.Add(root.val); // Add the root node to the path
traversal(root, targetSum - root.val); // Start the traversal
return result.Select(list => list as IList<int>).ToList();
}
// Recursive function to traverse the tree and find paths
private void traversal(TreeNode node, int count) {
// If a leaf node is reached and the target sum is achieved
if (node.left == null && node.right == null && count == 0) {
result.Add(new List<int>(path)); // Add a copy of the path to the result
return;
}
// If a leaf node is reached and the target sum is not achieved, or if it's not a leaf node
if (node.left == null && node.right == null) return;
// Traverse the left subtree
if (node.left != null) {
path.Add(node.left.val);
count -= node.left.val;
traversal(node.left, count); // Recursive call
count += node.left.val; // Backtrack
path.RemoveAt(path.Count - 1); // Backtrack
}
// Traverse the right subtree
if (node.right != null) {
path.Add(node.right.val);
count -= node.right.val;
traversal(node.right, count); // Recursive call
count += node.right.val; // Backtrack
path.RemoveAt(path.Count - 1); // Backtrack
}
}
}
// @lc code=end
```
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</a>

206
problems/0417.太平洋大西洋水流问题.md
View File

@ -562,7 +562,213 @@ function pacificAtlantic(heights) {
}
```
### go
dfs:
```go
var DIRECTIONS = [4][2]int{{-1, 0}, {1, 0}, {0, -1}, {0, 1}}
func pacificAtlantic(heights [][]int) [][]int {
res := make([][]int, 0)
pacific := make([][]bool, len(heights))
atlantic := make([][]bool, len(heights))
for i := 0; i < len(heights); i++ {
pacific[i] = make([]bool, len(heights[0]))
atlantic[i] = make([]bool, len(heights[0]))
}
// 列
for i := 0; i < len(heights); i++ {
dfs(heights, pacific, i, 0)
dfs(heights, atlantic, i, len(heights[0])-1)
}
// 行
for j := 0; j < len(heights[0]); j++ {
dfs(heights, pacific, 0, j)
dfs(heights, atlantic, len(heights)-1, j)
}
for i := 0; i < len(heights); i++ {
for j := 0; j < len(heights[0]); j++ {
if pacific[i][j] && atlantic[i][j] {
res = append(res, []int{i, j})
}
}
}
return res
}
func dfs(heights [][]int, visited [][]bool, i, j int) {
visited[i][j] = true
for _, d := range DIRECTIONS {
x, y := i+d[0], j+d[1]
if x < 0 || x >= len(heights) || y < 0 || y >= len(heights[0]) || heights[i][j] > heights[x][y] || visited[x][y] {
continue
}
dfs(heights, visited, x, y)
}
}
```
bfs:
```go
var DIRECTIONS = [4][2]int{{-1, 0}, {1, 0}, {0, -1}, {0, 1}}
func pacificAtlantic(heights [][]int) [][]int {
res := make([][]int, 0)
pacific := make([][]bool, len(heights))
atlantic := make([][]bool, len(heights))
for i := 0; i < len(heights); i++ {
pacific[i] = make([]bool, len(heights[0]))
atlantic[i] = make([]bool, len(heights[0]))
}
// 列
for i := 0; i < len(heights); i++ {
bfs(heights, pacific, i, 0)
bfs(heights, atlantic, i, len(heights[0])-1)
}
// 行
for j := 0; j < len(heights[0]); j++ {
bfs(heights, pacific, 0, j)
bfs(heights, atlantic, len(heights)-1, j)
}
for i := 0; i < len(heights); i++ {
for j := 0; j < len(heights[0]); j++ {
if pacific[i][j] && atlantic[i][j] {
res = append(res, []int{i, j})
}
}
}
return res
}
func bfs(heights [][]int, visited [][]bool, i, j int) {
queue := make([][]int, 0)
queue = append(queue, []int{i, j})
visited[i][j] = true
for len(queue) > 0 {
cur := queue[0]
queue = queue[1:]
for _, d := range DIRECTIONS {
x, y := cur[0]+d[0], cur[1]+d[1]
if x < 0 || x >= len(heights) || y < 0 || y >= len(heights[0]) || heights[cur[0]][cur[1]] > heights[x][y] || visited[x][y] {
continue
}
queue = append(queue, []int{x, y})
visited[x][y] = true
}
}
}
```
### Rust
dfs:
```rust
impl Solution {
const DIRECTIONS: [(isize, isize); 4] = [(0, 1), (0, -1), (1, 0), (-1, 0)];
pub fn pacific_atlantic(heights: Vec<Vec<i32>>) -> Vec<Vec<i32>> {
let (m, n) = (heights.len(), heights[0].len());
let mut res = vec![];
let (mut pacific, mut atlantic) = (vec![vec![false; n]; m], vec![vec![false; n]; m]);
// 列
for i in 0..m {
Self::dfs(&heights, &mut pacific, i, 0);
Self::dfs(&heights, &mut atlantic, i, n - 1);
}
for j in 0..n {
Self::dfs(&heights, &mut pacific, 0, j);
Self::dfs(&heights, &mut atlantic, m - 1, j);
}
for i in 0..m {
for j in 0..n {
if pacific[i][j] && atlantic[i][j] {
res.push(vec![i as i32, j as i32]);
}
}
}
res
}
pub fn dfs(heights: &[Vec<i32>], visited: &mut [Vec<bool>], i: usize, j: usize) {
visited[i][j] = true;
for (dx, dy) in Self::DIRECTIONS {
let (x, y) = (i as isize + dx, j as isize + dy);
if x < 0 || x >= heights.len() as isize || y < 0 || y >= heights[0].len() as isize {
continue;
}
let (x, y) = (x as usize, y as usize);
if !visited[x][y] && heights[x][y] >= heights[i][j] {
Self::dfs(heights, visited, x, y);
}
}
}
}
```
bfs:
```rust
use std::collections::VecDeque;
impl Solution {
const DIRECTIONS: [(isize, isize); 4] = [(0, 1), (0, -1), (1, 0), (-1, 0)];
pub fn pacific_atlantic(heights: Vec<Vec<i32>>) -> Vec<Vec<i32>> {
let (m, n) = (heights.len(), heights[0].len());
let mut res = vec![];
let (mut pacific, mut atlantic) = (vec![vec![false; n]; m], vec![vec![false; n]; m]);
// 列
for i in 0..m {
Self::bfs(&heights, &mut pacific, i, 0);
Self::bfs(&heights, &mut atlantic, i, n - 1);
}
for j in 0..n {
Self::bfs(&heights, &mut pacific, 0, j);
Self::bfs(&heights, &mut atlantic, m - 1, j);
}
for i in 0..m {
for j in 0..n {
if pacific[i][j] && atlantic[i][j] {
res.push(vec![i as i32, j as i32]);
}
}
}
res
}
pub fn bfs(heights: &[Vec<i32>], visited: &mut [Vec<bool>], i: usize, j: usize) {
let mut queue = VecDeque::from([(i, j)]);
visited[i][j] = true;
while let Some((i, j)) = queue.pop_front() {
for (dx, dy) in Self::DIRECTIONS {
let (x, y) = (i as isize + dx, j as isize + dy);
if x < 0 || x >= heights.len() as isize || y < 0 || y >= heights[0].len() as isize {
continue;
}
let (x, y) = (x as usize, y as usize);
if !visited[x][y] && heights[x][y] >= heights[i][j] {
queue.push_back((x, y));
visited[x][y] = true;
}
}
}
}
}
```
<p align="center">
<a href="https://programmercarl.com/other/kstar.html" target="_blank">

48
problems/0513.找树左下角的值.md
View File

@ -716,9 +716,55 @@ public void Traversal(TreeNode root, int depth)
return;
}
```
```csharp
/*
* @lc app=leetcode id=513 lang=csharp
* 迭代法
* [513] Find Bottom Left Tree Value
*/
// @lc code=start
public class Solution
{
public int FindBottomLeftValue(TreeNode root)
{
Queue<TreeNode> que = new Queue<TreeNode>();
if (root != null)
{
que.Enqueue(root);
}
int ans = 0;
while (que.Count != 0)
{
int size = que.Count;
for (var i = 0; i < size; i++)
{
var curNode = que.Peek();
que.Dequeue();
if(i == 0){
ans = curNode.val;
}
if (curNode.left != null)
{
que.Enqueue(curNode.left);
}
if (curNode.right != null)
{
que.Enqueue(curNode.right);
}
}
}
return ans;
}
}
// @lc code=end
```
<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"/>
</a>