Pacific Atlantic Water Flow

**Problem Statement:** Given the required input arguments, write an efficient algorithm to solve the **Pacific Atlantic Water Flow** problem. Implement the required logic as specified by standard definitions for this classic algorithmic challenge. **Hint / Expected Approach:** Reverse BFS from both ocean borders **Edge Cases to Consider:** - (1) 1×1 grid (both oceans) - (2) All same height - (3) No cell reaches both

Examples

Example 1

Input: [[1,2,2,3,5],[3,2,3,4,4],[2,4,5,3,1],[6,7,1,4,5],[5,1,1,2,4]]

Output: [[0,4],[1,3],[1,4],[2,2],[3,0],[3,1],[4,0]]

Explanation: Classic

Example 2

Input: [[1]]

Output: [[0,0]]

Explanation: 1×1 cell, both oceans

Example 3

Input: [[1,1],[1,1],[1,1]]

Output: All cells reachable

Explanation: All same height

Constraints

▪2 <= vertices <= 1000
▪0 <= edges <= 5000
▪Avoid infinite cycles during depth traversal

Watch Out For Edge Cases

▪1×1 grid (both oceans)
▪All same height
▪No cell reaches both

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