How to play Zip

Zip is LinkedIn's daily path puzzle. It looks like you just draw a line, but a few habits make it much faster. Here are the rules, a small example, and the tricks that solve most boards.

The rules

1. Draw one continuous line through every cell of the grid.
2. Start on 1 and pass the numbers in order: 1, 2, 3 and so on. The line ends on the highest number.
3. Move up, down, left or right. No diagonals, and the line can't cross itself.
4. Thick lines between cells are walls. The line can't go through them.

A new board comes out every day at 12:00 AM Pacific Time. Every official board has exactly one solution.

A small example

This 5×5 board is one of ours. Try it before you look at the answer below it.

Two clues get you started. The bottom-left corner holds 6, the last number, so the line finishes there. The top-left corner has only two neighbors, so the line must run straight through it. Follow those two clues and the left edge fills in quickly.

Strategy

1. Fill the corners first

A corner cell has only two neighbors, so the line must come in from one and leave by the other, unless the corner holds 1 or the last number. Cells boxed in by walls work the same way. Mark these links before anything else; they are free progress.

2. Don't strand a cell

After each move, look at the empty cells next to your line. If one of them is left with only one empty neighbor, it can only be the end of the path. Unless it holds the last number, your move was wrong.

3. Don't cut the board in two

If your line splits the empty cells into two areas that don't touch, you can't finish: once you go into one area, you can't come back for the other.

4. Use the number order

You can't step on a number until it is the next one. When two numbers in a row sit far apart, the stretch between them usually has to sweep a whole part of the board, often along an edge.

5. Work from both ends

The last number is fixed too. Trace backwards from it: the cells around it often leave only one way in.

6. The checkerboard check

Color the grid like a chessboard. Every step changes color, so any stretch of the line uses light and dark cells almost equally (at most one more of one color). If a pocket of the board that you must sweep in one go has two or more extra cells of one color, the plan can't work.

Where to go next

Today's Zip answer with hints · Past Zip answers

Want practice? Play Zip Unlimited: our own Zip-style puzzles, as many as you like.