Pacific Atlantic Water Flow: coding question

Problem

An island has the shape of a grid with m rows and n columns. The value heights[r][c] is the height of the cell at row r and column c.

The Pacific Ocean touches the top edge and the left edge of the island. The Atlantic Ocean touches the bottom edge and the right edge.

Rain water flows from a cell to a neighbor cell when the neighbor is not higher. A neighbor cell is directly above, below, left or right. Water flows from a cell on an edge into the ocean at that edge.

Return the coordinates [r, c] of every cell from which water can flow to both oceans. You can return the coordinates in any order.

Example 1

Input:: heights = [[1,2,3],[8,9,4],[7,6,5]]
Output:: [[0,2],[1,0],[1,1],[1,2],[2,0],[2,1],[2,2]]
Explanation:: Only the cells [0, 0] and [0, 1] are not in the answer. Water from them can flow only to the cell [0, 0], and all the neighbors of that cell are higher.

Example 2

Input:: heights = [[5]]
Output:: [[0,0]]
Explanation:: The single cell is on all four edges, so it touches both oceans.

Example 3

Input:: heights = [[2,2],[2,2]]
Output:: [[0,0],[0,1],[1,0],[1,1]]
Explanation:: Water flows between cells of equal height.

Constraints

m == heights.length
n == heights[r].length
1 <= m, n <= 200
0 <= heights[r][c] <= 10^5

SysRound wrote this statement. A reference solution checks every example.

Continue with questions that share topics or the same question type.

Calculate Trapping Rain Water
Coding
Container With Most Water
Coding · Array · Greedy · Two Pointers
Earliest Finish Time for Land and Water Rides I
Coding
Earliest Finish Time for Land and Water Rides II
Coding

Sources · 1 reference

These records explain where the question appears. A company tag or candidate report does not guarantee a future interview question.

Hello Interview · 4 records

Amazon
Leetcode 417. Pacific Atlantic Water Flow
Reported Nov 14, 2025 · 1 source report
MID_LEVEL
Source snapshot: Nov 12, 2026
View source
Merge
Leetcode 417. Pacific Atlantic Water Flow
Reported Apr 7, 2025 · 1 source report
SENIOR
Source snapshot: Nov 12, 2026
View source
Meta
Leetcode 417. Pacific Atlantic Water Flow
Reported Nov 27, 2024 · 1 source report
JUNIOR
Source snapshot: Nov 12, 2026
View source
Pinterest
Leetcode 417. Pacific Atlantic Water Flow
Reported Aug 4, 2026 · 1 source report
MID_LEVEL
Source snapshot: Nov 12, 2026

Problem

An island has the shape of a grid with m rows and n columns. The value heights[r][c] is the height of the cell at row r and column c.

The Pacific Ocean touches the top edge and the left edge of the island. The Atlantic Ocean touches the bottom edge and the right edge.

Return the coordinates [r, c] of every cell from which water can flow to both oceans. You can return the coordinates in any order.

Example 1

Input:: heights = [[1,2,3],[8,9,4],[7,6,5]]
Output:: [[0,2],[1,0],[1,1],[1,2],[2,0],[2,1],[2,2]]
Explanation:: Only the cells [0, 0] and [0, 1] are not in the answer. Water from them can flow only to the cell [0, 0], and all the neighbors of that cell are higher.

Example 2

Input:: heights = [[5]]
Output:: [[0,0]]
Explanation:: The single cell is on all four edges, so it touches both oceans.

Example 3

Input:: heights = [[2,2],[2,2]]
Output:: [[0,0],[0,1],[1,0],[1,1]]
Explanation:: Water flows between cells of equal height.

Constraints

m == heights.length
n == heights[r].length
1 <= m, n <= 200
0 <= heights[r][c] <= 10^5

SysRound wrote this statement. A reference solution checks every example.

Pacific Atlantic Water Flow

Problem

Example 1

Example 2

Example 3

Constraints

Related questions

Pacific Atlantic Water Flow

Problem

Example 1

Example 2

Example 3

Constraints

Related questions