Binary #629 · 10×10

• 10×10grid
• 22given cells
• 78to fill
• 22% given

Binary #629 is a 10×10 grid at hard level. 22 of its 100 cells are given, about 22 %, and the other 78 follow from the three rules.

The givens already show 5 pairs of equal symbols side by side. Close each pair with the opposite symbol at both ends: that is the quickest start.

There are 4 gaps between two equal givens. Each takes the opposite symbol.

One line already holds half of one symbol and can be filled with the other straight away.

Hard grids need the endgame rules: work out the ways a nearly full line can end, and remember that no two lines may be identical.