{"id":576,"date":"2025-12-17T17:00:17","date_gmt":"2025-12-17T04:00:17","guid":{"rendered":"https:\/\/thesudoku.com\/blog\/?page_id=576"},"modified":"2026-07-15T13:01:22","modified_gmt":"2026-07-15T01:01:22","slug":"swordfish","status":"publish","type":"page","link":"https:\/\/thesudoku.com\/blog\/swordfish\/","title":{"rendered":"Swordfish"},"content":{"rendered":"\n
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< <\/a>Back<\/a><\/p>\n<\/div>\n\n\n\n

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How to Master the Swordfish Strategy in Sudoku<\/p>\n\n\n\n

When even the famous X-Wing<\/em> technique leaves you stuck, it is time to deploy an even more powerful pattern-based strategy. The Swordfish technique<\/strong> is an advanced expert-level elimination method. The Swordfish technique is pretty similar to an \u201cX-Wing.\u201d<\/strong> However, instead of tracking a rectangle across two rows and columns, you will be scanning for a structural grid that spans across three rows and three columns<\/strong>.<\/p>\n\n\n\n

The Logic Behind the Swordfish Pattern<\/strong><\/h2>\n\n\n\n

A Swordfish pattern is formed when a single candidate is restricted to a maximum of three cells in three parallel lines (rows or columns), and all these cells perfectly align into the exact same three perpendicular lines.<\/p>\n\n\n\n

Consider the following example:<\/strong><\/p>\n\n\n\n

Imagine we are tracking the number 6<\/strong> across three horizontal rows (for example: Row 2, Row 6, and Row 9). When filling out your pencil notes, you notice that:<\/p>\n\n\n\n

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\"Swordfish<\/figure>\n\n\n\n
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  1. In Row 2, the number 6 can only go into Column 6 and Column 8.<\/li>\n\n\n\n
  2. In Row 6, the number 6 can only go into Column 3 and Column 6.<\/li>\n\n\n\n
  3. In Row 9, the number 6 can only go into Column 3, Column 6 and Column 8.<\/li>\n<\/ol>\n\n\n\n

    Even though none of the rows contain three candidates, all these occurrences fit perfectly within Columns 3, 6, and 8<\/strong>.<\/p>\n\n\n\n

    Because every row must<\/em> contain a 6, and these three rows share a closed loop of three columns, it is mathematically guaranteed that the 6s will occupy the intersecting corners of this 3×3 grid. No matter how you try to place them, those three rows will completely absorb the 6s for those three columns.<\/p>\n\n\n\n

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    \"Swordfish<\/figure>\n\n\n\n
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    The Power of Elimination (Step-by-Step)<\/strong><\/h2>\n\n\n\n

    As these rows are guaranteed to contain 6 in the highlighted cells,<\/strong> those three vertical lines are now completely locked by the Swordfish pattern. Therefore, 6 can\u2019t be placed in other cells within the given columns.<\/strong><\/p>\n\n\n\n

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    \"Swordfish<\/figure>\n\n\n\n
    \n<\/div>\n\n\n\n

    To apply this to your game, follow these steps:<\/strong><\/p>\n\n\n\n

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    1. Pick a number:<\/strong> Track a stubborn candidate (like 6) across the entire board.<\/li>\n\n\n\n
    2. Find Three Parallel Lines:<\/strong> Look for three rows where that candidate appears two or three times maximum.<\/li>\n\n\n\n
    3. Verify the Alignment:<\/strong> Check if all these candidates fall into the exact same three vertical columns. If they do, your Swordfish is locked!<\/li>\n\n\n\n
    4. Clear the Intersecting Lines:<\/strong> Go to those three columns and delete the number 6 from the pencil notes of every other cell<\/strong> along those lines, making sure to leave the Swordfish corners untouched.<\/li>\n<\/ol>\n\n\n\n

      Swordfish Variations: Rows vs. Columns<\/strong><\/h2>\n\n\n\n

      Like most advanced grid techniques, a Swordfish can develop in two ways:<\/p>\n\n\n\n