Given a binary tree, find its minimum depth.
The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.
Note: A leaf is a node with no children.
Example 1:
Input: root = [3,9,20,null,null,15,7] Output: 2
Example 2:
Input: root = [2,null,3,null,4,null,5,null,6] Output: 5
Constraints:
- The number of nodes in the tree is in the range
[0, 105]. -1000 <= Node.val <= 1000
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def minDepth(self, root: Optional[TreeNode]) -> int:
if root is None:
return 0
if root.left is None:
return 1 + self.minDepth(root.right)
if root.right is None:
return 1 + self.minDepth(root.left)
return 1 + min(self.minDepth(root.left), self.minDepth(root.right))# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def minDepth(self, root: Optional[TreeNode]) -> int:
if root is None:
return 0
q = deque([root])
ans = 0
while 1:
ans += 1
for _ in range(len(q)):
node = q.popleft()
if node.left is None and node.right is None:
return ans
if node.left:
q.append(node.left)
if node.right:
q.append(node.right)/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
public int minDepth(TreeNode root) {
if (root == null) {
return 0;
}
if (root.left == null) {
return 1 + minDepth(root.right);
}
if (root.right == null) {
return 1 + minDepth(root.left);
}
return 1 + Math.min(minDepth(root.left), minDepth(root.right));
}
}/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
public int minDepth(TreeNode root) {
if (root == null) {
return 0;
}
Deque<TreeNode> q = new ArrayDeque<>();
q.offer(root);
int ans = 0;
while (true) {
++ans;
for (int n = q.size(); n > 0; n--) {
TreeNode node = q.poll();
if (node.left == null && node.right == null) {
return ans;
}
if (node.left != null) {
q.offer(node.left);
}
if (node.right != null) {
q.offer(node.right);
}
}
}
}
}/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
int minDepth(TreeNode* root) {
if (!root) {
return 0;
}
if (!root->left) {
return 1 + minDepth(root->right);
}
if (!root->right) {
return 1 + minDepth(root->left);
}
return 1 + min(minDepth(root->left), minDepth(root->right));
}
};/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
int minDepth(TreeNode* root) {
if (!root) {
return 0;
}
queue<TreeNode*> q{{root}};
int ans = 0;
while (1) {
++ans;
for (int n = q.size(); n; --n) {
auto node = q.front();
q.pop();
if (!node->left && !node->right) {
return ans;
}
if (node->left) {
q.push(node->left);
}
if (node->right) {
q.push(node->right);
}
}
}
}
};/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
func minDepth(root *TreeNode) int {
if root == nil {
return 0
}
if root.Left == nil {
return 1 + minDepth(root.Right)
}
if root.Right == nil {
return 1 + minDepth(root.Left)
}
return 1 + min(minDepth(root.Left), minDepth(root.Right))
}
func min(a, b int) int {
if a < b {
return a
}
return b
}/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
func minDepth(root *TreeNode) (ans int) {
if root == nil {
return 0
}
q := []*TreeNode{root}
for {
ans++
for n := len(q); n > 0; n-- {
node := q[0]
q = q[1:]
if node.Left == nil && node.Right == nil {
return
}
if node.Left != nil {
q = append(q, node.Left)
}
if node.Right != nil {
q = append(q, node.Right)
}
}
}
}/**
* Definition for a binary tree node.
* function TreeNode(val, left, right) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
*/
/**
* @param {TreeNode} root
* @return {number}
*/
var minDepth = function (root) {
if (!root) {
return 0;
}
if (!root.left) {
return 1 + minDepth(root.right);
}
if (!root.right) {
return 1 + minDepth(root.left);
}
return 1 + Math.min(minDepth(root.left), minDepth(root.right));
};/**
* Definition for a binary tree node.
* function TreeNode(val, left, right) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
*/
/**
* @param {TreeNode} root
* @return {number}
*/
var minDepth = function (root) {
if (!root) {
return 0;
}
const q = [root];
let ans = 0;
while (1) {
++ans;
for (let n = q.length; n; --n) {
const node = q.shift();
if (!node.left && !node.right) {
return ans;
}
if (node.left) {
q.push(node.left);
}
if (node.right) {
q.push(node.right);
}
}
}
};/**
* Definition for a binary tree node.
* class TreeNode {
* val: number
* left: TreeNode | null
* right: TreeNode | null
* constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
* }
*/
function minDepth(root: TreeNode | null): number {
if (root == null) {
return 0;
}
const { left, right } = root;
if (left == null) {
return 1 + minDepth(right);
}
if (right == null) {
return 1 + minDepth(left);
}
return 1 + Math.min(minDepth(left), minDepth(right));
}/**
* Definition for a binary tree node.
* class TreeNode {
* val: number
* left: TreeNode | null
* right: TreeNode | null
* constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
* }
*/
function minDepth(root: TreeNode | null): number {
if (!root) {
return 0;
}
const q = [root];
let ans = 0;
while (1) {
++ans;
for (let n = q.length; n; --n) {
const node = q.shift();
if (!node.left && !node.right) {
return ans;
}
if (node.left) {
q.push(node.left);
}
if (node.right) {
q.push(node.right);
}
}
}
}// Definition for a binary tree node.
// #[derive(Debug, PartialEq, Eq)]
// pub struct TreeNode {
// pub val: i32,
// pub left: Option<Rc<RefCell<TreeNode>>>,
// pub right: Option<Rc<RefCell<TreeNode>>>,
// }
//
// impl TreeNode {
// #[inline]
// pub fn new(val: i32) -> Self {
// TreeNode {
// val,
// left: None,
// right: None
// }
// }
// }
use std::rc::Rc;
use std::cell::RefCell;
impl Solution {
fn dfs(root: &Option<Rc<RefCell<TreeNode>>>) -> i32 {
if root.is_none() {
return 0;
}
let node = root.as_ref().unwrap().borrow();
if node.left.is_none() {
return 1 + Self::dfs(&node.right);
}
if node.right.is_none() {
return 1 + Self::dfs(&node.left);
}
1 + Self::dfs(&node.left).min(Self::dfs(&node.right))
}
pub fn min_depth(root: Option<Rc<RefCell<TreeNode>>>) -> i32 {
Self::dfs(&root)
}
}/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* struct TreeNode *left;
* struct TreeNode *right;
* };
*/
#define min(a, b) (((a) < (b)) ? (a) : (b))
int minDepth(struct TreeNode* root) {
if (!root) {
return 0;
}
if (!root->left) {
return 1 + minDepth(root->right);
}
if (!root->right) {
return 1 + minDepth(root->left);
}
int left = minDepth(root->left);
int right = minDepth(root->right);
return 1 + min(left, right);
}