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???Minimum Distance in a Star Graph

热度:47   发布时间:2023-11-03 00:55:17.0

In this problem, we will define a graph called star graph, and the question is to find the minimum distance between two given nodes in the star graph.

Given an integer nn, an n-dimensionaln?dimensional star graph, also referred to as S_{n}S?n??, is an undirected graph consisting of n!n! nodes (or vertices) and ((n-1)\ *\ n!)/2((n?1) ? n!)/2 edges. Each node is uniquely assigned a label x_{1}\ x_{2}\ ...\ x_{n}x?1?? x?2?? ... x?n??which is any permutation of the n digits {1, 2, 3, ..., n}1,2,3,...,n. For instance, an S_{4}S?4?? has the following 24 nodes {1234, 1243, 1324, 1342, 1423, 1432, 2134, 2143, 2314, 2341, 2413, 2431, 3124, 3142, 3214, 3241, 3412, 3421, 4123, 4132, 4213, 4231, 4312, 4321}1234,1243,1324,1342,1423,1432,2134,2143,2314,2341,2413,2431,3124,3142,3214,3241,3412,3421,4123,4132,4213,4231,4312,4321. For each node with label x_{1}\ x_{2} x_{3}\ x_{4}\ ...\ x_{n}x?1?? x?2??x?3?? x?4?? ... x?n??, it has n-1n?1 edges connecting to nodes x_{2}\ x_{1}\ x_{3}\ x_{4}\ ...\ x_{n}x?2?? x?1?? x?3?? x?4?? ... x?n??x_{3}\ x_{2}\ x_{1}\ x_{4}\ ...\ x_{n}x?3?? x?2?? x?1?? x?4?? ... x?n??x_{4}\ x_{2}\ x_{3}\ x_{1}\ ...\ x_{n}x?4?? x?2?? x?3?? x?1?? ... x?n??, ..., and x_{n}\ x_{2}\ x_{3}\ x_{4}\ ...\ x_{1}x?n?? x?2?? x?3?? x?4?? ... x?1??. That is, the n-1n?1 adjacent nodes are obtained by swapping the first symbol and the d-thd?th symbol of x_{1}\ x_{2}\ x_{3}\ x_{4}\ ...\ x_{n}x?1?? x?2?? x?3?? x?4?? ... x?n??, for d = 2, ..., nd=2,...,n. For instance, in S_{4}S?4??, node 12341234 has 33 edges connecting to nodes 2134213432143214, and 42314231. The following figure shows how S_{4}S?4?? looks (note that the symbols aabbcc, and dd are not nodes; we only use them to show the connectivity between nodes; this is for the clarity of the figure).

In this problem, you are given the following inputs:

  • nn: the dimension of the star graph. We assume that nn ranges from 44 to 99.
  • Two nodes x_{1}x?1?? x_{2}x?2?? x_{3}x?3?? ... x_{n}x?n?? and y_{1}y?1?? y_{2}y?2?? y_{3}\ ...\ y_{n}y?3?? ... y?n?? in S_{n}S?n??.

You have to calculate the distance between these two nodes (which is an integer).

Input Format

nn (dimension of the star graph)

A list of 55 pairs of nodes.

Output Format

A list of 55 values, each representing the distance of a pair of nodes.

样例输入

4
1234 4231
1234 3124
2341 1324
3214 4213
3214 2143

样例输出

1
2
2
1
3

题目来源

2017 ACM-ICPC 亚洲区(南宁赛区)网络赛

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