Chain Sudoku – Medium

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"Chain Sudoku," also known as "Strimko," is a logic puzzle that involves filling circles arranged in a square grid with digits. Some circles contain clues (pre-filled numbers), while others are empty and need to be filled by the solver. The grid also contains several chains, which are sets of connected circles.

Basic Rules

1. Digit Placement: Fill every empty circle with a digit from 1-9.
2. Unique Digits: Each digit from 1-9 must appear exactly once in each row and column of the grid.

Additional Rules

1. Chain Rule: In addition to the rows and columns, each chain must also contain the digits 1-9 exactly once.

Basic Solving Tips

• Start with Clues: Begin by looking at the rows, columns, and chains that have the most clues. These will guide you to place digits in the empty circles.
• Avoid Repetition: Ensure that no digit is repeated in any row, column, or chain.
• Use Elimination: Identify which numbers cannot be in a particular circle and eliminate them as possibilities.
• Look for Certainties: Before placing a number, make sure it is the only possibility for that circle.
• Chain Consideration: Pay special attention to the chains, ensuring that the digits within them adhere to the rules.