Num-link solver

There are puzzles in which the same numbers are connected by lines.
This puzzle is unique in that it is more often solved by intuition or on-the-spot inspiration rather than by careful accumulation of logic.
It is practically impossible to solve these puzzles by logic, but this application, Nanrin Solver, uses the smartphone's CPU to verify all patterns and solve the puzzle.
These puzzles are often published in puzzle magazines and newspapers, but as I mentioned earlier, they take a considerable amount of time to solve.
Of course, puzzle magazines exist to help you kill that kind of time, but if you don't want to spend that kind of time and want to solve puzzles quickly, this is the puzzle for you.
Some puzzles can be solved in less than a second, while others can take several hours, depending on the pattern of the problem.
While your smartphone is solving the puzzle, the app also allows you to listen to music to pass the time.
Note that there are no examples or practice problems in this app. This app is only specialized for solving puzzles.
How to use
1. Look at a puzzle in a newspaper or magazine, and tap to input the board size and number sequence.
　Instead of numbers, you can use animal pictograms or fruit pictograms. (Optional)
2. Select one of the playlists registered in the "Music" application to take some time while the application solves the puzzle.
When you have finished entering the puzzle board, press the "Solve" button and the app will start solving the puzzle. Please wait until the puzzle is solved while listening to the music in the playlist you have selected.
When the puzzle is solved, or you find that there is no solution, you will receive a push notification, so please start the app to check the solution.

Rules of this puzzle
1.Draw lines in the squares and connect the same numbers.
2.The lines must be drawn vertically and horizontally so that they go through the squares. Lines must not cross each other or branch off.
3. Lines must not pass through numbered squares.
4. No more than two lines may be drawn in a square.