Leetcode 305. Number of Islands II
Given an initially all-water m×n grid, process a sequence of add-land operations and return the number of islands (4-directionally connected land components) after each addition. The problem requires maintaining dynamic connectivity efficiently—typically via Union-Find (disjoint set) with handling for duplicate adds and frequent merges.
Asked at:
Uber
Microsoft
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Late June, 2026
Uber
Mid-level
Essentially the same question but structured in a restaurant context where I had to design a class with methods like openRestaurant and getDeliveryZones
Late March, 2026
Uber
Senior
The question was not esactly in the same wordings. create an data-structure that supports the following operations. addLand(x, y) - marks (x,y) as an land isLand(x, y) - returns True if (x,y) is a land else False extension 1: add a functionality : getIslands() - returns the number of inlands that we have. (x,y) are 4-directionally connected extension 2: add one more function: addBridge(location1, location2) - location1 and location2 are two different land points. addBridge connects these two points. (Note : we are not asked to find the bridge i.e adding land masses to connect these two it should simple connect these two points.)
Mid February, 2026
Uber
Mid-level
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