GraphMatrixDFSMulti-source
A grid of heights is bordered by the Pacific Ocean on the top and left edges and the Atlantic Ocean on the bottom and right edges. Water flows from a cell to a neighbouring cell (up, down, left or right) whose height is equal or lower. Find every cell from which water can flow to both oceans.
Input
Line 1: r and c. Next r lines: c heights each.
Output
Print each qualifying cell as 'row column' (0-based) on its own line, in ascending row then column order.
Constraints
1 <= r, c <= 15 0 <= height <= 9
Example 1
Input
2 2 1 1 1 1
Output
0 0 0 1 1 0 1 1
On a flat grid every cell reaches both oceans.