Algorithm - LeetCode Problems 12

Problem 1305. All Elements in Two Binary Search Trees

• Given two binary search trees root1 and root2, return a list containing all the integers from both trees sorted in ascending order.

Examples

• Example 1
  • Input: root1 = [2,1,4], root2 = [1,0,3]
  • Output: [0,1,1,2,3,4]

• Example 2
  • Input: root1 = [1,null,8], root2 = [8,1]
  • Output: [1,1,8,8]

Constraints

• The number of nodes in each tree is in the range [0, 5000].
• -10^5 <= Node.val <= 10^5

Solution

/**
 * 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} root1
 * @param {TreeNode} root2
 * @return {number[]}
 */
var getAllElements = function(root1, root2) {
    const result = [];

    const dfs = (node1, node2) => {
        if (!node1 && !node2) {
            return;
        }

        if (node1) {
            result.push(node1.val);
            if (node1.left) {
                dfs(node1.left);
            }
            if (node1.right) {
                dfs(node1.right);
            }
        }

        if (node2) {
            result.push(node2.val);
            if (node2.left) {
                dfs(node2.left);
            }
            if (node2.right) {
                dfs(node2.right);
            }
        }
    };

    dfs(root1, root2);
    return result.sort((a,b) => a - b);
}

Problem 1268. Search Suggestions System

• You are given an array of strings products and a string searchWord.

• Design a system that suggests at most three product names from products after each character of searchWord is typed. Suggested products should have common prefix with searchWord. If there are more than three products with a common prefix return the three lexicographically minimums products.

• Return a list of lists of the suggested products after each character of searchWord is typed.

Examples

• Example 1:

  • Input: products = ["mobile","mouse","moneypot","monitor","mousepad"], searchWord = "mouse"
  • Output: [["mobile","moneypot","monitor"],["mobile","moneypot","monitor"],["mouse","mousepad"],["mouse","mousepad"],["mouse","mousepad"]]
    Explanation:
    • products sorted lexicographically = ["mobile","moneypot","monitor","mouse","mousepad"].
    • After typing m and mo all products match and we show user ["mobile","moneypot","monitor"].
    • After typing mou, mous and mouse the system suggests ["mouse","mousepad"].

• Example 2:

  • Input: products = ["havana"], searchWord = "havana"
  • Output: [["havana"],["havana"],["havana"],["havana"],["havana"],["havana"]]
  • Explanation:
    • The only word "havana" will be always suggested while typing the search word.

Constraints

• 1 <= products.length <= 1000
• 1 <= products[i].length <= 3000
• 1 <= sum(products[i].length) <= 2 * 10^4
• All the strings of products are unique.
• products[i] consists of lowercase English letters.
• 1 <= searchWord.length <= 1000
• searchWord consists of lowercase English letters.

Solution

/**
 * @param {string[]} products
 * @param {string} searchWord
 * @return {string[][]}
 */
var suggestedProducts = function(products, searchWord) {
    const result = [];
    products.sort();

    for (let i = 1; i <= searchWord.length; i++) {
        const prefix = searchWord.substring(0,i);
        const commonPrefixProducts = [];
        
        for (let j = 0; j < products.length; j++) {
            if (commonPrefixProducts.length >= 3) {
                break;
            }
            const product = products[j];
            if (product.startsWith(prefix)) {
                commonPrefixProducts.push(product);
            }
        }

        result.push(commonPrefixProducts);
    }
    
    return result;
};

Problem 226. Invert Binary Tree

• Given the root of a binary tree, invert the tree, and return its root.

Examples

• Example 1
  • Input: root = [4,2,7,1,3,6,9]
  • Output: [4,7,2,9,6,3,1]

• Example 2
  • Input: root = [2,1,3]
  • Output: [2,3,1]

Constraints

• The number of nodes in the tree is in the range [0, 100].
• -100 <= Node.val <= 100

Solution

/**
 * 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 {TreeNode}
 */
var invertTree = function(root) {
    const queue = [root];

    while (queue.length) {
        const node = queue.shift();
        if (node) {
            const temp = node.left;
            node.left = node.right;
            node.right = temp;
            queue.push(node.left, node.right);
        }
    }
    
    return root;
};