Finding all possible combinations

- In the problem zero three folder of my testing site,…I've created a file called queens dot php.…You can find this in the exercise files…for this video.…It contains some simple code to keep track…of how long the script takes to execute…and defines a constant called board size…and sets its value to eight.…That's the size of the chessboard.…We know that two queens can never be in the same…row or column, so we can use a loop to represent…the eight rows, each of which will contain…a queen in a different column.…

So let's have that loop.…We'll initialize row at zero.…We'll use the board size to control the loop,…and increment row each time we go through the loop.…Inside there we'll create an array called layout.…We'll give it the index of row, and then assign…the value of one, and then use the bit wise…shift left operator and the value of row.…

So this will generate binary numbers that shift…the bits the same number of places as the value…of the counter row.…The first time the loop runs row is zero,…so no bits are moved.…