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Overview
Basic Data Structures
Basic Algorithms
Same Direction
Opposite Direction
Sliding Window
Cycle Finding
Speedrun
DFS on Tree
Binary Search Tree
Combinatorial Search
Additional States
Aggregation and Memoization
Additional Practices
Speedrun
Vanilla BFS
Matrix as Graph
Implicit Graph
Directed Graph / Topological Sort
Weighted Graph
Minimum Spanning Tree
Introduction
Dynamic number of subproblems
Knapsack
Additional Practices
Disjoint Set Union | Union Find
Data Structure Design
Segment Tree
Monotonic Stack
Line Sweep
Tree Traversal without Recursion
Amazon OA
Microsoft OA
Google OA
Editorials
Prereq: BFS on Graph
Given a 2-dimensional matrix of values with 0 and 1, count the number of islands of 1. An island consists of all 1 value cells and is surrounded by either an edge or all 0 cells. Cells can only be adjacent to each other horizontally or vertically, not diagonally.
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