Leetcode

1962. Remove Stones to Minimize the Total Hardness: \(\color{orange}\textsf{Medium}\) Ralated Topics: Array、Heap (Priority Queue) 一、題目 You are given a 0-indexed integer array piles, where piles[i] represents the number of stones in the ith pile, and an integer k. You should apply the following operation exactly k times: Choose any piles[i] and remove floor(piles[i] / 2) stones from it. Notice that you can apply the operation on the same pile more than once. Return the minimum possible total number of stones remaining after applying the k operations. floor(x) is the greatest integer that is smaller than or equal to x (i.e., rounds x down). ...

2279. Maximum Bags With Full Capacity of Rocks Hardness: \(\color{orange}\textsf{Medium}\) Ralated Topics: Array、Greedy、Sorting 一、題目 You have n bags numbered from 0 to n - 1. You are given two 0-indexed integer arrays capacity and rocks. The ith bag can hold a maximum of capacity[i] rocks and currently contains rocks[i] rocks. You are also given an integer additionalRocks, the number of additional rocks you can place in any of the bags. Return the maximum number of bags that could have full capacity after placing the additional rocks in some bags. ...

2389. Longest Subsequence With Limited Sum Hardness: \(\color{green}\textsf{Easy}\) Ralated Topics: Array、Binary Search、Greedy、Sorting、Prefix Sum 一、題目 You are given an integer array nums of length n, and an integer array queries of length m. Return an array answer of length m where answer[i] is the maximum size of a subsequence that you can take from nums such that the sum of its elements is less than or equal to queries[i]. A subsequence is an array that can be derived from another array by deleting some or no elements without changing the order of the remaining elements. ...

790. Domino and Tromino Tiling Hardness: \(\color{orange}\textsf{Medium}\) Ralated Topics: Dynamic Programming 一、題目 You have two types of tiles: a 2 x 1 domino shape and a tromino shape. You may rotate these shapes. Given an integer n, return the number of ways to tile an 2 x n board. Since the answer may be very large, return it modulo 10^9 + 7. In a tiling, every square must be covered by a tile. Two tilings are different if and only if there are two 4-directionally adjacent cells on the board such that exactly one of the tilings has both squares occupied by a tile. ...

841. Keys and Rooms Hardness: \(\color{orange}\textsf{Medium}\) Ralated Topics: Depth-First Search、Breadth-First Search、Graph 一、題目 There are n rooms labeled from 0 to n - 1 and all the rooms are locked except for room 0. Your goal is to visit all the rooms. However, you cannot enter a locked room without having its key. When you visit a room, you may find a set of distinct keys in it. Each key has a number on it, denoting which room it unlocks, and you can take all of them with you to unlock the other rooms. Given an array rooms where rooms[i] is the set of keys that you can obtain if you visited room i, return true if you can visit all the rooms, or false otherwise. ...

25. Reverse Nodes in k-Group Hardness: \(\color{red}\textsf{Hard}\) Ralated Topics: Linked List、Recursion 一、題目 Given the head of a linked list, reverse the nodes of the list k at a time, and return the modified list. k is a positive integer and is less than or equal to the length of the linked list. If the number of nodes is not a multiple of k then left-out nodes, in the end, should remain as it is. You may not alter the values in the list’s nodes, only nodes themselves may be changed. ...

24. Swap Nodes in Pairs Hardness: \(\color{orange}\textsf{Medium}\) Ralated Topics: Linked List、Recursion 一、題目 Given a linked list, swap every two adjacent nodes and return its head. You must solve the problem without modifying the values in the list’s nodes (i.e., only nodes themselves may be changed.) Example 1: Input: head = [1,2,3,4] Output: [2,1,4,3] Example 2: Input: head = [] Output: [] Example 3: Input: head = [1] Output: [1] Constraints: ...

931. Minimum Falling Path Sum Hardness: \(\color{orange}\textsf{Medium}\) Ralated Topics: Array、Dynamic Programming、Matrix 一、題目 Given an n x n array of integers matrix, return the minimum sum of any falling path through matrix. A falling path starts at any element in the first row and chooses the element in the next row that is either directly below or diagonally left/right. Specifically, the next element from position (row, col) will be (row + 1, col - 1), (row + 1, col), or (row + 1, col + 1). ...

70. Climbing Stairs Hardness: \(\color{green}\textsf{Easy}\) Ralated Topics: Math、Dynamic Programming、Memoization 一、題目 You are climbing a staircase. It takes n steps to reach the top. Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top? Example 1: Input: n = 2 Output: 2 Explanation: There are two ways to climb to the top. 1 step + 1 step 2 steps Example 2: ...

2501. Longest Square Streak in an Array Hardness: \(\color{orange}\textsf{Medium}\) Ralated Topics: Array、Hash Table、Binary Search、Dynamic Programming、Sorting \(\color{blue}\textsf{Weekly Contest 323}\) 一、題目 You are given an integer array nums. A subsequence of nums is called a square streak if: The length of the subsequence is at least 2, and after sorting the subsequence, each element (except the first element) is the square of the previous number. Return the length of the longest square streak in nums, or return -1 if there is no square streak. A subsequence is an array that can be derived from another array by deleting some or no elements without changing the order of the remaining elements. Example 1: ...