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Solve grid path and top‑k frequency
This question evaluates algorithmic problem-solving in grid reachability and frequency analysis, testing concepts such as grid/graph traversal and obstacle handling for path existence alongside frequency counting and selection for top-k elements.
Part A — Grid Reachability with Obstacles: Given an m×n matrix of 0s and 1s where 0 indicates a passable cell and 1 indicates a blocked cell, starting at (0, 0) determine whether there exists a path to the bottom-right cell (m−1,n− 1). You may move up, down, left, or right within bounds and cannot enter blocked cells. Return true if such a path exists, otherwise false.
Part B — Top‑K Frequent Numbers: Given an array of integers and an integer k, return the k numbers that appear most frequently in the array. If multiple numbers have the same frequency, any order among them is acceptable.
Grid Reachability With Obstacles
Return whether a 4-neighbor path exists from top-left to bottom-right through zero cells.
Examples
Example 1
Input: ([[0,0],[1,0]],)
Output: True
Explanation: Path exists.
Example 2
Input: ([[0,1],[1,0]],)
Output: False
Explanation: No path through obstacles.
Hints
- Clarify edge cases before coding.
- Keep the return value deterministic.
Top K Frequent Numbers
Return the k most frequent numbers, breaking ties by smaller numeric value.
Examples
Example 1
Input: ([1,1,1,2,2,3], 2)
Output: [1, 2]
Explanation: Return top two by frequency.
Example 2
Input: ([4,4,5,5,6], 2)
Output: [4, 5]
Explanation: Ties are broken by numeric value for deterministic output.
Hints
- Clarify edge cases before coding.
- Keep the return value deterministic.