thảo luận Leetcode mỗi ngày

# 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 getDirections(self, root: Optional[TreeNode], startValue: int, destValue: int) -> str:
        parent_dict = dict()
        node_dict = dict()
        def dfs(p: TreeNode, node: TreeNode):
            if not node:
                return
            node_dict[node.val] = node
            parent_dict[node.val] = p
            dfs(node, node.left)
            dfs(node, node.right)
        
        def get_height(node: TreeNode):
            h = 0
            while parent_dict[node.val]:
                h += 1
                node = parent_dict[node.val]
            return h
        
        dfs(None, root)
        
        start_node_height = get_height(node_dict[startValue])
        dest_node_height = get_height(node_dict[destValue])

        start_directions = []
        dest_directions = []

        start_node = node_dict[startValue]
        dest_node = node_dict[destValue]

        while start_node_height > dest_node_height:
            start_directions.append("U")
            start_node = parent_dict[start_node.val]
            start_node_height -= 1
        
        while dest_node_height > start_node_height:
            p = parent_dict[dest_node.val]
            if p.left == dest_node:
                dest_directions.append('L')
            else:
                dest_directions.append('R')
            dest_node = p
            dest_node_height -= 1
        
        while start_node != dest_node:
            start_directions.append("U")
            start_node = parent_dict[start_node.val]

            p = parent_dict[dest_node.val]
            if p.left == dest_node:
                dest_directions.append('L')
            else:
                dest_directions.append('R')
            dest_node = p
        return "".join(start_directions + list(reversed(dest_directions)))

/**
 * 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
 * @param {number} startValue
 * @param {number} destValue
 * @return {string}
 */
var getDirections = function (root, startValue, destValue) {
    let leftPath = '';
    let rightPath = '';
    function findPathToNode(root, path) {
        if (!root) return;
        if (root.val === startValue) {
            leftPath = path;
        } else if (root.val === destValue) {
            rightPath = path;
        }
        if (leftPath && rightPath) return;
        findPathToNode(root.left, path+'L');
        findPathToNode(root.right, path+'R');
    }
    findPathToNode(root, '');
    let isDiff = false;
    let i = 0;
    while (!isDiff && (i < leftPath.length && i < rightPath.length)) {
        if (!isDiff && leftPath[i] === rightPath[i]) {
            leftPath = leftPath.slice(1);
            rightPath = rightPath.slice(1);
            continue;
        }
        isDiff = true;
        i++;
    }
    return "U".repeat(leftPath.length)+rightPath;
};

function delNodes(root: TreeNode | null, to_delete: number[]): Array<TreeNode | null> {
    const q: TreeNode[] = [];
    const res: TreeNode[] = [];
    const arr = new Array(1001).fill(false);
    for (const item of to_delete) arr[item] = true;
    q.push(root);
    while (q.length) {
        const node = q.shift();
        if (node.left) {
            q.push(node.left);
            if (arr[node.left.val]) node.left = null;
        }
        if (node.right) {
            q.push(node.right);
            if (arr[node.right.val]) node.right = null;
        }

        if (arr[node.val]) {
            if (node.left) res.push(node.left);
            if (node.right) res.push(node.right);
        }
    }
    if (!arr[root.val]) res.push(root);
    return res;
};

//Problem: https://leetcode.com/problems/delete-nodes-and-return-forest/
class Solution {
    func delNodes(_ root: TreeNode?, _ to_delete: [Int]) -> [TreeNode?] {
        var rootAns = [TreeNode?]()
        if let delRoot = delNode(root, to_delete, &rootAns) {
            rootAns.append(delRoot)
        }
        return rootAns
    }
    
    func delNode(_ root: TreeNode?, _ to_delete: [Int], _ listRoot: inout [TreeNode?]) -> TreeNode? {
        guard let root else { return nil }
        
        root.left = delNode(root.left, to_delete, &listRoot)
        root.right = delNode(root.right, to_delete, &listRoot)
        if to_delete.contains(root.val) {
            if root.left != nil { listRoot.append(root.left) }
            if root.right != nil { listRoot.append(root.right) }
            return nil
        }
        return root
    }
}

var delNodes = function(root, to_delete) {
    const delete_set = new Set(to_delete);
    const ans = [];
    const dfs = (node) => {
        if (!node) return node;

        node.left = dfs(node.left);
        node.right = dfs(node.right);

        if (!delete_set.has(node.val)) return node;
        if (node.left) ans.push(node.left);
        if (node.right) ans.push(node.right);
        return null;
    }

    const r = dfs(root);
    if (r) ans.push(r);

    return ans;
};

class Solution {
    func delNodes(_ root: TreeNode?, _ to_delete: [Int]) -> [TreeNode?] {
        guard let root else { return []}
        var setDel = Set(to_delete)
       
        var result:[TreeNode] = []
        func dfs(_ node: TreeNode?, deletedParent: Bool) -> Bool { // is node exist
            guard let node else { return false }
            if setDel.remove(node.val) != nil {
                dfs(node.left, deletedParent: true)
                dfs(node.right, deletedParent: true)
                return false
            }
            if !dfs(node.left, deletedParent: false) {
                node.left = nil
            }
            if !dfs(node.right, deletedParent: false) {
                node.right = nil
            }
           
            if deletedParent {
                result.append(node)
            }
            return true
        }
        dfs(root, deletedParent: true)
        return result
    }
}

class Solution {
    public List<TreeNode> delNodes(TreeNode root, int[] to_delete) {
        List<TreeNode> forest = new ArrayList();
        Queue<TreeNode> queue = new LinkedList();
        queue.add(root);
        int[] del = new int[1001];
        for (int i : to_delete) {
            del[i] = 1;
        }
        if(del[root.val] != 1) forest.add(root);
        List<TreeNode> nodes = new ArrayList();
        while (!queue.isEmpty()) {
            TreeNode node = queue.poll();
            TreeNode left = node.left;
            TreeNode right = node.right;
            if (left != null) {
                queue.add(left);
                if (del[left.val] == 1) {
                    node.left = null;
                    left=null;
                }
            }
            if (right != null) {
                queue.add(right);
                if (del[right.val] == 1) {
                    node.right = null;
                    right=null;
                }
            }
            if (del[node.val] == 1) {
                if (left != null) {
                    forest.add(left);
                }
                if (right != null) {
                    forest.add(right);
                }
            }
        }
        return forest;
    }
}

class Solution:
    def delNodes(self, root: Optional[TreeNode], to_delete: List[int]) -> List[TreeNode]:
        forest = []
        toDeleteSet = set(to_delete)

        def deleteNodes(root):
            if not root:
                return
            root.left = deleteNodes(root.left)
            root.right = deleteNodes(root.right)
            if root.val in toDeleteSet:
                forest.extend(node for node in (root.left, root.right) if node)
                return None
            return root
        
        deleteNodes(root)
        if root.val not in toDeleteSet:
            forest.append(root)
        return forest

impl Solution {
    pub fn del_nodes(
        root: Option<Rc<RefCell<TreeNode>>>,
        to_delete: Vec<i32>,
    ) -> Vec<Option<Rc<RefCell<TreeNode>>>> {
        fn delete_nodes(
            root: Rc<RefCell<TreeNode>>,
            to_delete: &mut std::collections::HashSet<i32>,
            forest: &mut Vec<Option<Rc<RefCell<TreeNode>>>>,
        ) {
            let mut node = root.as_ref().borrow_mut();
            let should_remove_root = to_delete.contains(&node.val);

            if should_remove_root {
                to_delete.remove(&node.val);
            }

            if let Some(left) = node.left.clone() {
                if to_delete.contains(&left.as_ref().borrow().val) {
                    node.left = None;
                }
                delete_nodes(left, to_delete, forest);
            }

            if let Some(right) = node.right.clone() {
                if to_delete.contains(&right.as_ref().borrow().val) {
                    node.right = None;
                }
                delete_nodes(right, to_delete, forest);
            }

            if should_remove_root {
                if node.left.is_some() {
                    forest.push(node.left.clone())
                }
                if node.right.is_some() {
                    forest.push(node.right.clone())
                }
            }
        }

        if let Some(node) = root {
            let mut to_delete: std::collections::HashSet<_> = to_delete.into_iter().collect();
            let mut forest = if to_delete.contains(&node.as_ref().borrow().val) {
                Vec::new()
            } else {
                vec![Some(node.clone())]
            };
            delete_nodes(node.clone(), &mut to_delete, &mut forest);
            forest
        } else {
            Vec::new()
        }
    }
}

impl Solution {
    pub fn del_nodes(root: Option<Rc<RefCell<TreeNode>>>, to_delete: Vec<i32>) -> Vec<Option<Rc<RefCell<TreeNode>>>> {
        fn delete_nodes(root: Option<Rc<RefCell<TreeNode>>>, to_delete: &std::collections::HashSet<i32>, forest: &mut Vec<Option<Rc<RefCell<TreeNode>>>>) -> Option<Rc<RefCell<TreeNode>>> {
            if let Some(ref node) = root {
                let mut node = node.as_ref().borrow_mut();

                (node.left, node.right) = (
                    delete_nodes(node.left.clone(), to_delete, forest),
                    delete_nodes(node.right.clone(), to_delete, forest),
                );

                if to_delete.contains(&node.val) {
                    if node.left.is_some() {
                        forest.push(node.left.clone());
                    }
                    if node.right.is_some() {
                        forest.push(node.right.clone());
                    }
                    return None
                }
             
                return root.clone()
            }
         
            None
        }

        let (mut to_delete, mut forest) = (to_delete.into_iter().collect(), Vec::new());
        if delete_nodes(root.clone(), &to_delete, &mut forest).is_some() {
            forest.push(root)
        }
        forest
    }
}

impl Solution {
    pub fn del_nodes(root: Option<Rc<RefCell<TreeNode>>>, to_delete: Vec<i32>) -> Vec<Option<Rc<RefCell<TreeNode>>>> {
        fn delete_nodes(root: &Option<Rc<RefCell<TreeNode>>>, to_delete: &std::collections::HashSet<i32>, forest: &mut Vec<Option<Rc<RefCell<TreeNode>>>>) -> Option<Rc<RefCell<TreeNode>>> {
            if let Some(node) = root {
                let mut node = node.as_ref().borrow_mut();              

                (node.left, node.right) = (
                    delete_nodes(&node.left, to_delete, forest),
                    delete_nodes(&node.right, to_delete, forest),
                );

                if to_delete.contains(&node.val) {
                    if node.left.is_some() {
                        forest.push(node.left.clone());
                    }
                    if node.right.is_some() {
                        forest.push(node.right.clone());
                    }
                    return None
                }
               
                return root.clone()
            }
           
            None
        }

        let (to_delete, mut forest) = (to_delete.into_iter().collect(), Vec::new());
        if delete_nodes(&root, &to_delete, &mut forest).is_some() {
            forest.push(root)
        }
        forest
    }
}

function delNodes(root: TreeNode | null, to_delete: number[]): TreeNode[] {
    const result: TreeNode[] = [];
    const deleteSet = new Set(to_delete);

    function dfs(node: TreeNode | null, isRoot: boolean): TreeNode | null {
        if (!node) return null;

        const isDeleted = deleteSet.has(node.val);

        if (isRoot && !isDeleted) {
            result.push(node);
        }

        node.left = dfs(node.left, isDeleted);
        node.right = dfs(node.right, isDeleted);

        return isDeleted ? null : node;
    }

    dfs(root, true);
    return result;
}