欠一数对 Almost Locked Pair

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Example

We set B1=X (X=27). In Box 2, X and 3 must be in A6 and C6, so candidates of that two cells are all 2, 3 and 7.

ALP is complex in real puzzle. It's covert when two or more basic types are overlapping.

Example 1 Entanglement

This situation can be seen as Firework either, but we can regard it as ALP.

If I7 and I8 are 7 and 8, numbers cannot fill the Column 9. So there are at most one 7 or 8 in I7 and I8. At last, we can know I2=78, F9=78, I2≠F9.

Example 2 Entanglement

C1=45, so C1 cannot contain other numbers.

Example 3 Unknown Cover

练习 Practice

① Find the next hint with ALP.

答案 Answer

① A9=2 (Hidden Singles in Box 3).