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摘要： Graph: n nodes, m edges Representation Adjacency Matrix: O(n^2) space, not efficient for sparse graph Adjacency List: O(n + m) space, efficient for sp 阅读全文

摘要： There are N piles of stones arranged in a row. The i-th pile has stones[i] stones. A move consists of merging exactly K consecutive piles into one pil 阅读全文

摘要： Given an array A of 0s and 1s, we may change up to K values from 0 to 1. Return the length of the longest (contiguous) subarray that contains only 1s. 阅读全文

摘要： We are given that the string "abc" is valid. From any valid string V, we may split V into two pieces X and Y such that X + Y (X concatenated with Y) i 阅读全文

摘要： Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list. Example 1: Example 2: 阅读全文

摘要： Given an array of integers A, find the sum of min(B), where B ranges over every (contiguous) subarray of A. Since the answer may be large, return the 阅读全文

摘要： On a N x N grid of cells, each cell (x, y) with 0 <= x < N and 0 <= y < N has a lamp. Initially, some number of lamps are on. lamps[i] tells us the lo 阅读全文

摘要： In an array A containing only 0s and 1s, a K-bit flip consists of choosing a (contiguous) subarray of length K and simultaneously changing every 0 in 阅读全文

摘要： Consider all the leaves of a binary tree. From left to right order, the values of those leaves form a leaf value sequence. For example, in the given t 阅读全文

摘要： This problem was asked by Google. In a directed graph, each node is assigned an uppercase letter. We define a path's value as the number of most frequ 阅读全文