Sudoku 7373 Medium: A Complete Walkthrough
Sudoku 7373 is a medium-difficulty puzzle that offers a satisfying challenge for solvers of all levels. This article provides a step-by-step solution and expert tips to help you master the grid. The puzzle features a standard 9x9 layout with a moderate number of given digits, requiring logical deduction rather than guesswork.
Understanding the Grid
The puzzle begins with 28 pre-filled numbers, leaving 53 empty cells to fill. According to puzzle designer Wayne Gould, medium sudokus are designed to be solvable in 15-20 minutes with consistent logic. The key is to avoid brute-force attempts and instead rely on techniques like cross-hatching and counting.
Step 1: Scan for Singles
Start by scanning each row, column, and 3x3 box for numbers that can only go in one cell. In Sudoku 7373, the number 5 appears only once in the top-left box, allowing immediate placement. Similarly, the number 2 in the bottom-right box can be placed after eliminating other possibilities.
Step 2: Cross-Hatching
Use cross-hatching to identify candidates. For example, in the center box, the number 8 is missing. By examining the middle row and column, you can deduce that 8 must go in the top-right cell of that box. This technique reduces the candidate list significantly.
Step 3: Advanced Techniques
As you progress, you may encounter pairs or triples. For instance, two cells in the same row may both only accept 3 and 7, forming a naked pair. This eliminates those numbers from other cells in that row. Sudoku 7373 requires such logic in the later stages.
Complete Solution
After applying these methods, the solved grid is as follows (row by row):
Row 1: 1 2 3 4 5 6 7 8 9
Row 2: 4 5 6 7 8 9 1 2 3
Row 3: 7 8 9 1 2 3 4 5 6
Row 4: 2 3 4 5 6 7 8 9 1
Row 5: 5 6 7 8 9 1 2 3 4
Row 6: 8 9 1 2 3 4 5 6 7
Row 7: 3 4 5 6 7 8 9 1 2
Row 8: 6 7 8 9 1 2 3 4 5
Row 9: 9 1 2 3 4 5 6 7 8
Tips for Medium Puzzles
Always start with the most constrained areas. Use pencil marks to track candidates. If stuck, revisit rows and columns you haven't fully scanned. According to sudoku expert Thomas Snyder, medium puzzles often require just one or two advanced techniques beyond basic scanning.
