I went with DFS and chose to mutate the grid by flipping visited 1s to 0s.
Clarify the problem constraints and edge cases, then propose a depth-first search (DFS) or breadth-first search (BFS) traversal from the given cell to count connected land cells. Discuss mutating the grid versus using a visited set, and analyze time and space complexity.
Pro tip: Mention that mutating the grid to mark visited cells is often preferred in interviews for its O(1) space overhead, but always ask if mutation is allowed. Also, explicitly handle out-of-bounds and water cells as base cases to avoid errors.
Restate the problem, confirm input types, and discuss edge cases such as out-of-bounds indices, water cells, and empty grid. Ask if grid mutation is permitted.
Decide between DFS (recursive or iterative) and BFS. Explain your choice based on constraints like grid size and recursion depth limits.
For DFS: base cases are out-of-bounds, water, or already visited. Otherwise, mark visited and recursively explore all four directions, summing counts.
Write pseudocode or code, then trace through a small example to verify correctness, including edge cases.
State time complexity O(N) where N is number of cells in the island, and space complexity O(N) for recursion stack or visited set. Discuss trade-offs between mutation and extra space.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
Basically just wrap the original function in a loop over every cell and track the max.
Clarify that the problem is to find the maximum island size in a binary grid, likely after changing at most one 0 to 1. Use DFS/BFS with union-find to compute island sizes, then evaluate each 0 by summing the sizes of adjacent distinct islands plus one. Handle edge cases like no zeros or all ones.
Pro tip: Mention that you would first solve the simpler 'max island size without flipping' to establish a baseline, then extend it, showing incremental problem-solving and awareness of Apple's emphasis on clean, efficient code.
Confirm whether the task is to find the largest island after changing at most one 0 to 1, and discuss constraints like grid size and whether diagonal connections count.
Decide between DFS/BFS with a visited set or union-find. Union-find is often cleaner for this problem because it efficiently tracks island sizes and merges components.
Traverse the grid to identify all islands, assign each a unique ID, and record their sizes using union-find or DFS/BFS.
For each 0, collect the unique IDs of adjacent islands, sum their sizes, add 1 for the flipped cell, and update the maximum.
If there are no zeros, return the size of the largest existing island. Otherwise, return the maximum found in step 4.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.