LinkedIn Zip Solver

How to Use the Zip Solver

This tool solves any LinkedIn Zip puzzle. Choose your grid size (5×5 through 9×9), then click cells to place hint numbers in order. The first click places hint 1, the second places hint 2, and so on. Once you've placed at least two hints, click "Solve Puzzle" to find the solution.

The solver uses a backtracking algorithm with Warnsdorff's heuristic to find a Hamiltonian path that visits every cell exactly once while passing through your hints in sequence and respecting wall barriers. Use the step-by-step viewer to walk through the solution at your own pace.

How the solver actually works

Zip is a constrained Hamiltonian path problem: find a route that enters every cell on the grid exactly once, passes through the numbered hints in ascending order, and never crosses a wall. Finding Hamiltonian paths is NP-complete in general, so the solver does not try every route — on a 7×7 board that would be astronomically many. It prunes instead.

Three things do the work. Backtracking walks the path forward one cell at a time and rewinds the moment a move leads nowhere. Warnsdorff's heuristic decides which neighbour to try first, always preferring the cell with the fewest remaining exits — the same instinct behind sweeping the edges and corners before the open middle. Connectivity pruning is the one that matters most: after each move the solver checks whether the unvisited cells still form a single reachable region, and abandons the branch immediately if the path has cut the board in two. That single check eliminates the overwhelming majority of dead ends before they are ever explored.

A worked example

Take a 6×6 grid with hint 1 in the top-left corner. The corner has only two exits, right and down, so Warnsdorff tries it first and the branching factor stays low from move one. Suppose the path then runs straight across the top row and turns down the right edge. The solver checks connectivity and finds the remaining 24 cells still form one connected block — fine, keep going. Now suppose instead it had dived into the middle of the board on move three: the unvisited cells would split into two pockets, and since a single continuous path cannot visit both, the solver discards that entire branch without exploring any of it. This is exactly the mistake human players make and only notice twenty moves later.

Limits worth knowing

• It stops at two million steps. The solver runs in your browser, so it caps its own search to avoid freezing the tab. If it hits that cap it tells you rather than pretending no solution exists — re-check your hint placement and try again.
• “No solution” usually means a typo. Most unsolvable boards entered by hand have a hint in the wrong cell or a missing wall. A genuine LinkedIn Zip board always has at least one valid path.
• It returns one path, not all of them. Some boards have several valid solutions; the solver stops at the first it proves correct. It will be a legal answer, but it need not be the one you were halfway through drawing.
• Nothing leaves your device. The grid you enter is solved locally in JavaScript — no board is uploaded or stored.

Looking for Today's Answer?

If you'd rather not re-enter a board by hand, our LinkedIn Zip Answers archive already has the solved path for each day, and you can step through it one cell at a time. New to the puzzle? Start with how to play LinkedIn Zip.