A5
Non-adjacent Constraint
不相邻约束
Arrangement / 排列组合Grades G5 - G8
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What It Looks Like
Recognition signals — when you see these, think of this structure:
- 1Cannot sit together
- 2Must be separated
- 3Not adjacent condition
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What It Really Tests
The core mathematical idea behind this structure:
Forbidden neighbors are handled by placing main items first, then using gaps.
不能相邻的处理方法: 先放主要元素, 再在空隙中插入。
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Why Students Get Stuck
Common mistakes to watch out for:
- ⚠Trying random arrangements and checking each one
- ⚠Not using the gap/slot structure
- ⚠Forgetting edge gaps (before first and after last)
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Your First Step
How to begin thinking about problems with this structure:
Place the main objects first and identify the available gaps.
先放主要对象, 再找可用的空隙。
Related Structures
These structures share similar patterns or thinking approaches: