Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string.
Note: You must not use any built-in BigInteger library or convert the inputs to integer directly.
Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string.
Note: You must not use any built-in BigInteger library or convert the inputs to integer directly.
1589. Maximum Sum Obtained of Any Permutation
We have an array of integers, nums, and an array of requests where requests[i] = [starti, endi]. The ith request asks for the sum of nums[starti] + nums[starti + 1] + … + nums[endi - 1] + nums[endi]. Both starti and endi are 0-indexed.
Return the maximum total sum of all requests among all permutations of nums.
Since the answer may be too large, return it modulo 109 + 7.
971. Flip Binary Tree To Match Preorder Traversal
You are given the root of a binary tree with n nodes, where each node is uniquely assigned a value from 1 to n. You are also given a sequence of n values voyage, which is the desired pre-order traversal of the binary tree.
Any node in the binary tree can be flipped by swapping its left and right subtrees. For example, flipping node 1 will have the following effect:
Flip the smallest number of nodes so that the pre-order traversal of the tree matches voyage.
Return a list of the values of all flipped nodes. You may return the answer in any order. If it is impossible to flip the nodes in the tree to make the pre-order traversal match voyage, return the list [-1].
You are given an integer n which indicates that we have n courses, labeled from 1 to n. You are also given an array relations where relations[i] = [a, b], representing a prerequisite relationship between course a and course b: course a has to be studied before course b.
In one semester, you can study any number of courses as long as you have studied all the prerequisites for the course you are studying.
Return the minimum number of semesters needed to study all courses. If there is no way to study all the courses, return -1.
423. Reconstruct Original Digits from English
Given a non-empty string containing an out-of-order English representation of digits 0-9, output the digits in ascending order.
Note:
- Input contains only lowercase English letters.
- Input is guaranteed to be valid and can be transformed to its original digits. That means invalid inputs such as “abc” or “zerone” are not permitted.
- Input length is less than 50,000.
1805. Number of Different Integers in a String
You are given a string word that consists of digits and lowercase English letters.
You will replace every non-digit character with a space. For example, “a123bc34d8ef34” will become “ 123 34 8 34”. Notice that you are left with some integers that are separated by at least one space: “123”, “34”, “8”, and “34”.
Return the number of different integers after performing the replacement operations on word.
Two integers are considered different if their decimal representations without any leading zeros are different.
1806. Minimum Number of Operations to Reinitialize a Permutation
You are given an even integer n. You initially have a permutation perm of size n where perm[i] == i (0-indexed).
In one operation, you will create a new array arr, and for each i:
- If i % 2 == 0, then arr[i] = perm[i / 2].
- If i % 2 == 1, then arr[i] = perm[n / 2 + (i - 1) / 2].
You will then assign arr to perm.
Return the minimum non-zero number of operations you need to perform on perm to return the permutation to its initial value.
1807. Evaluate the Bracket Pairs of a String
You are given a string s that contains some bracket pairs, with each pair containing a non-empty key.
- For example, in the string “(name)is(age)yearsold”, there are two bracket pairs that contain the keys “name” and “age”.
You know the values of a wide range of keys. This is represented by a 2D string array knowledge where each knowledge[i] = [keyi, valuei] indicates that key keyi has a value of valuei.
You are tasked to evaluate all of the bracket pairs. When you evaluate a bracket pair that contains some key keyi, you will:
- Replace keyi and the bracket pair with the key’s corresponding valuei.
- If you do not know the value of the key, you will replace keyi and the bracket pair with a question mark “?” (without the quotation marks).
Each key will appear at most once in your knowledge. There will not be any nested brackets in s.
Return the resulting string after evaluating all of the bracket pairs.
1808. Maximize Number of Nice Divisors
You are given a positive integer primeFactors. You are asked to construct a positive integer n that satisfies the following conditions:
- The number of prime factors of n (not necessarily distinct) is at most primeFactors.
- The number of nice divisors of n is maximized. Note that a divisor of n is nice if it is divisible by every prime factor of n. For example, if n = 12, then its prime factors are [2,2,3], then 6 and 12 are nice divisors, while 3 and 4 are not.
Return the number of nice divisors of n. Since that number can be too large, return it modulo 109 + 7.
Note that a prime number is a natural number greater than 1 that is not a product of two smaller natural numbers. The prime factors of a number n is a list of prime numbers such that their product equals n.
