[LeetCode] Escape a Large Maze

1036. Escape a Large Maze

There is a 1 million by 1 million grid on an XY-plane, and the coordinates of each grid square are (x, y).

We start at the source = [sx, sy] square and want to reach the target = [tx, ty] square. There is also an array of blocked squares, where each blocked[i] = [xi, yi] represents a blocked square with coordinates (xi, yi).

Each move, we can walk one square north, east, south, or west if the square is not in the array of blocked squares. We are also not allowed to walk outside of the grid.

Return true if and only if it is possible to reach the target square from the source square through a sequence of valid moves.

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[LeetCode] Number of Paths with Max Score

1301. Number of Paths with Max Score

You are given a square board of characters. You can move on the board starting at the bottom right square marked with the character ‘S’.

You need to reach the top left square marked with the character ‘E’. The rest of the squares are labeled either with a numeric character 1, 2, …, 9 or with an obstacle ‘X’. In one move you can go up, left or up-left (diagonally) only if there is no obstacle there.

Return a list of two integers: the first integer is the maximum sum of numeric characters you can collect, and the second is the number of such paths that you can take to get that maximum sum, taken modulo 10^9 + 7.

In case there is no path, return [0, 0].

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[LeetCode] Best Time to Buy and Sell Stock

121. Best Time to Buy and Sell Stock

You are given an array prices where prices[i] is the price of a given stock on the ith day.

You want to maximize your profit by choosing a single day to buy one stock and choosing a different day in the future to sell that stock.

Return the maximum profit you can achieve from this transaction. If you cannot achieve any profit, return 0.

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[LeetCode] Smallest Subtree with all the Deepest Nodes

865. Smallest Subtree with all the Deepest Nodes

Given the root of a binary tree, the depth of each node is the shortest distance to the root.

Return the smallest subtree such that it contains all the deepest nodes in the original tree.

A node is called the deepest if it has the largest depth possible among any node in the entire tree.

The subtree of a node is a tree consisting of that node, plus the set of all descendants of that node.

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[LeetCode] Remove Duplicates from Sorted List II

82. Remove Duplicates from Sorted List II

Given the head of a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list. Return the linked list sorted as well.

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[LeetCode] Bulb Switcher II

672. Bulb Switcher II

There is a room with n bulbs labeled from 1 to n that all are turned on initially, and four buttons on the wall. Each of the four buttons has a different functionality where:

  • Button 1: Flips the status of all the bulbs.
  • Button 2: Flips the status of all the bulbs with even labels (i.e., 2, 4, …).
  • Button 3: Flips the status of all the bulbs with odd labels (i.e., 1, 3, …).
  • Button 4: Flips the status of all the bulbs with a label j = 3k + 1 where k = 0, 1, 2, … (i.e., 1, 4, 7, 10, …).

You must make exactly presses button presses in total. For each press, you may pick any of the four buttons to press.

Given the two integers n and presses, return the number of different possible statuses after performing all presses button presses.

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[LeetCode] Maximum Product of Splitted Binary Tree

1339. Maximum Product of Splitted Binary Tree

Given the root of a binary tree, split the binary tree into two subtrees by removing one edge such that the product of the sums of the subtrees is maximized.

Return the maximum product of the sums of the two subtrees. Since the answer may be too large, return it modulo 109 + 7.

Note that you need to maximize the answer before taking the mod and not after taking it.

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[LeetCode] Find the Most Competitive Subsequence

1673. Find the Most Competitive Subsequence

Given an integer array nums and a positive integer k, return the most competitive subsequence of nums of size k.

An array’s subsequence is a resulting sequence obtained by erasing some (possibly zero) elements from the array.

We define that a subsequence a is more competitive than a subsequence b (of the same length) if in the first position where a and b differ, subsequence a has a number less than the corresponding number in b. For example, [1,3,4] is more competitive than [1,3,5] because the first position they differ is at the final number, and 4 is less than 5.

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[LeetCode] Minimum Operations to Make a Subsequence

1713. Minimum Operations to Make a Subsequence

You are given an array target that consists of distinct integers and another integer array arr that can have duplicates.

In one operation, you can insert any integer at any position in arr. For example, if arr = [1,4,1,2], you can add 3 in the middle and make it [1,4,3,1,2]. Note that you can insert the integer at the very beginning or end of the array.

Return the minimum number of operations needed to make target a subsequence of arr.

A subsequence of an array is a new array generated from the original array by deleting some elements (possibly none) without changing the remaining elements’ relative order. For example, [2,7,4] is a subsequence of [4,2,3,7,2,1,4] (the underlined elements), while [2,4,2] is not.

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[LeetCode] Abbreviating the Product of a Range

2117. Abbreviating the Product of a Range

You are given two positive integers left and right with left <= right. Calculate the product of all integers in the inclusive range [left, right].

Since the product may be very large, you will abbreviate it following these steps:

    1. Count all trailing zeros in the product and remove them. Let us denote this count as C.
  • For example, there are 3 trailing zeros in 1000, and there are 0 trailing zeros in 546.
    1. Denote the remaining number of digits in the product as d. If d > 10, then express the product as <pre>...<suf> where <pre> denotes the first 5 digits of the product, and <suf>denotes the last 5 digits of the product after removing all trailing zeros. If d <= 10, we keep it unchanged.
  • For example, we express 1234567654321 as 12345…54321, but 1234567 is represented as 1234567.
    1. Finally, represent the product as a string "<pre>...<suf>eC".
  • For example, 12345678987600000 will be represented as “12345…89876e5”.

Return a string denoting the abbreviated product of all integers in the inclusive range [left, right].

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