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Mountain Trail 山路小径

Mountain Trail曾出现于第23届WPC Round 2 第5题。

规则

Mountain Trail,23rd WPC Instrucion Booklet © 2014, UK Puzzle Association
Mountain Trail,23rd WPC Instrucion Booklet © 2014, UK Puzzle Association
规则
从表格左上角的旗帜开始, 画一条环状的路径回到原点。这条路径必须经过表格中除了树以外的每个格子。而路径本身只能直向或横向连接, 且不能碰到或跨越自己。
表格本身以阴影深浅分成三个区域, 白色区域代表地势最低的山脚下, 而最深色的区域则代表山顶。路径必须从山脚一路往上走到山顶后再一路走回山脚, 所以整条路径只会依序分成五个阶段 - 山脚区, 斜坡区, 山顶区, 斜坡区, 山脚区。
Rule
Draw a trail which starts and ends at the flag in the top left corner of the grid and visits every cell except for those occupied by a tree. The trail moves orthogonally between the centre of cells and does not touch or cross itself. The grid is divided into 3 regions by shading. Lighter shading represents the lower slopes of a mountain and darker shading represents the summit region of the mountain. The trail starts and finishes in the unshaded lowland region and makes a single ascent of the mountain and a single descent i.e. the trail has only 5 sections: lowland, lower slopes, summit region, lower slopes, lowland.
Mountain Trail答案,23rd WPC Instrucion Booklet © 2014, UK Puzzle Association
Mountain Trail答案,23rd WPC Instrucion Booklet © 2014, UK Puzzle Association

解题技巧

  • 如同基本题型, 先把部分只有one way 的格子标出路径。
  • 困难的点就是要从哪一格进入山坡, 再上山顶, 再从哪格下山坡, 再由哪格回到山脚。若是把格子间隔以奇偶做区分, 则若是第一格进入的是奇, 那麽最后一格出来的也一定是奇。接著再去找代表奇数的格子哪几格可能出来, 最后就会减少可能性。当进出的格子都找到, 答案就很简单了。

参考资料