Rules:

This puzzle has Parks (empty cells). The goal is to fill in each cell with numbers from 1 to N-(No. of Parks), where N is the size of the puzzle's side.

Each column and each row have exactly one of each number and one park.

The numbers along the edge of the puzzle indicate the number of buildings which you would see from that direction if there was a series of skyscrapers with heights equal the entries in that row or column.

For example: if the grid is 4 and if the first number is 4, you will see only one skyscraper (the one with 4 floors) because it hides all other skyscrapers (those with 1, 2, 3 floors).

This puzzle has a Diagonal Variant. Every diagonal line contains each of the digits only once.