Saddle Points

Instructions

Your task is to find the potential trees where you could build your tree house.

The data company provides the data as grids that show the heights of the trees. The rows of the grid represent the east-west direction, and the columns represent the north-south direction.

An acceptable tree will be the largest in its row, while being the smallest in its column.

A grid might not have any good trees at all. Or it might have one, or even several.

Here is a grid that has exactly one candidate tree.

      ↓
      1  2  3  4
    |-----------
  1 | 9  8  7  8
→ 2 |[5] 3  2  4
  3 | 6  6  7  1

• Row 2 has values 5, 3, 2, and 4. The largest value is 5.
• Column 1 has values 9, 5, and 6. The smallest value is 5.

So the point at [2, 1] (row: 2, column: 1) is a great spot for a tree house.

Input format

The input will be in the format of a string. To keep this exercise beginner-friendly, you need not expect numbers with multiple digits.

Bytes 64-191 of the linear memory are reserved for the input string.

Output format

The output is expected in pairs of row and column as u8 directly concatenated.

For example, if there are three saddle points

row: 2, column: 1 row: 2, column: 2 row: 2, column: 3

then the expected output would be the u8 values 2, 1, 2, 2, 2, 3

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Source

J Dalbey's Programming Practice problems