Number Logic Puzzle 1969
The goal is to fill in each cell with numbers from 1 to N, where N is the size of the puzzle's side.
Each column and each row contain the numbers only once.
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 line has 4 cells and if the first number in the cell is 4, you will see only one skyscraper because the 4-floor skyscraper hides the 1-floor, 2-floor, and 3-floor skyscrapers.