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Leetcode Problem 305. Number of Islands II

305. Number of Islands II

Leetcode Solutions

Key approach of the solution: Union-Find

  1. Define the Union-Find class with methods find, union, addLand, isLand, and numberOfIslands.
  2. Initialize the Union-Find instance with a size of m * n.
  3. Iterate over each position in positions and convert the 2D cell to a 1D index.
  4. Add the land to the Union-Find structure and increment the island count.
  5. Check all four neighbors of the new land cell. If a neighbor is land, perform a union operation.
  6. After each land addition, append the current number of islands to the answer list.
  7. Return the answer list containing the number of islands after each addition.
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Key approach of the solution: Depth-First Search (DFS)

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