Andrew Stankevich’s Contest #4
ZOJ2559 The Smart Bomb 53.76% (321/597)
ZOJ2560 I Just Called … 21.05% (76/361)
ZOJ2561 Order-Preserving Codes 18.28% (126/689)
ZOJ2562 More Divisors 30.14% (322/1068)
ZOJ2563 Long Dominoes 37.94% (148/390)
ZOJ2564 The Magic Wheel 17.11% (83/485)
ZOJ2565 Cracking SSH 50.25% (98/195)
ZOJ2566 Periodic Tilings 33.81% (47/139)
ZOJ2567 Trade 16.66% (97/582)
ZOJ2568 Counting Triangulations 16.31% (101/619)
ZOJ2569 Unfair Contest 28.57% (64/224)

### ZOJ2559 The Smart Bomb

$\left\{\begin{array}{l}x+y=c\\y+z=a\\z+x=b\end{array}\right.$

### ZOJ2560 I Just Called …

source code (ZOJ2560.java) [trie, if-else]

### ZOJ2562 More Divisors

source code (ZOJ2562.cpp) [math, number theory]

### ZOJ2564 The Magic Wheel

source code (ZOJ2564.cpp) [math, enumeration]

### ZOJ2566 Periodic Tilings

source code (ZOJ2566.cpp) [math, graph]

* World Finals – 2004/2005
* Shanghai (China)
* G. Tiling the Plane
You might find the following information useful: It is known that there are only two fundamentally different tilings of the plane, the regular tiling by squares (chessboard tiling) and the tiling by regular hexagons (honeycomb tiling). A polygon can therefore tile the plane if and only if it satisfies one of the following two conditions:
1. There are points A, B, C, D in order on the polygon boundary (the points are not necessarily vertices of the polygon) such that the polygon boundaries from A to B and from D to C are congruent and the boundaries from B to C and from A to D are congruent. This leads to a tiling equivalent to the square tiling.
2. There are points A, B, C, D, E, F in order on the polygon boundary, such that the boundary pairs AB and ED, BC and FE, CD and AF are congruent. This leads to a tiling equivalent to the hexagon tiling.

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*.*
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source code (ZOJ2567.cpp) [FlowNetwork]

### ZOJ2568 Counting Triangulations

• count(A,B,C)=sum{count(P,B,C)*count(A,P,C)*count(A,B,P)}，\forall P 在三角形ABC内
• count(A,B,C)=1，三角形ABC内无点

，用count2(a,b)表示由a,a+1,…,b-1,b这些点组成的凸多边形，那么有：

• count2(a,b)=sum{count2(a,i)*count(a,b,i)*count(i,b)}, i = a+1,….,b-1

### ZOJ2569 Unfair Contest

6 Responses to “Andrew Stankevich’s Contest #4解题报告”
1. shllhs says:

能问一下平面覆盖那题判断条件为什么是w[i][i+m]<=3?

• watashi says:

看WF2005的G题的那段英文题目描述里说了这个结论

2. 复活也有 says:

有木有qq啊！！可不可以加q啊！

3. haha says:

大牛 能发份ZOJ 2567的数据吗 用了一个模板 看了半天找不出哪里错了

• watashi says:

不提供数据

• haha says:

多谢大牛回复 问题已经解决了 打错了一个变量。。。

4.