URAL 1614. National Project “Trams” 构造
2015-03-22 22:24
288 查看
1614. National Project “Trams”
Time limit: 0.5 secondMemory limit: 64 MB
President has declared the development of tram service a priority national project. As a part of this project, Yekaterinburg will receive enough budget funds to carry out a complete reconstruction of
the city's tram network.
There are 2n tram stops in Yekaterinburg. In the course of reconstruction, the stops will be left in their places and no new stops will be built, but new tram railways will be laid so that
it will be possible to go by tram from every tram stop to any other tram stop without any intermediate stops.
Having studied messages at the tram forum, the city authorities found out that citizens would be satisfied with the reconstruction only if for every pair of tram stops there would be a tram route connecting
these stops without any intermediate stops. It is clear that the network of n(2n − 1) routes consisting of only two stops each satisfies this requirement. However, Yekaterinburg Mayor wants exactly n routes to be left after the reconstruction,
and each tram must make exactly 2n stops (including the final ones) on its route. Trams must go along these routes in both directions. Suggest a plan of reconstruction that will satisfy both citizens and Mayor.
Input
The only input line contains the integer n, 1 ≤ n ≤ 100.Output
Output n lines describing tram routes. Each route is a sequence of integers in the range from 1 to 2n separated by a space. A route may go through a stop several times. If the problemhas several solutions, you may output any of them. If there is no solution, output one line containing the number −1.
Sample
input | output |
---|---|
3 | 1 6 2 1 3 4 |
Problem Source: The 12th Urals Collegiate Programing Championship, March 29, 2008
Tags: tricky problem (
hide tags for unsolved problems
)
题意:
输出n行,每行2*n个数。要求这2*n个数字能 两两相邻。
做法:
因为相邻的一共有n*(n-1)/2 对, 而把2*n个数字 两两互连,也是 n*(n-1)/2 对,所以每两个数之间是不能重复相邻的。
所以两侧 肯定是 123456 ,各个数字都出现一遍。
构造的方法是看别人的,首尾互取,然后把数列往后推1格,再首尾互取。
以n=3为例:
123456,
首尾互取 162534 为第一行
234561
首尾互取 213645 为第二行
345612
首尾互取 324156 为第三行
#include <cstdio> #include <cstring> #include <iostream> using namespace std; int N, M; int main() { int i, j, k; cin>>N; M = N*2; for (i = 0; i < N; ++i) { int now = i; for (j = 0; j < N; ++j) { printf("%d %d",(j+now)%M+1,(M-1-j+now)%M+1); if(j!=N-1) printf(" "); } puts(""); } return 0; }
相关文章推荐
- URAL 1614. National Project “Trams” [ 构造 欧拉回路 ]
- URAL 1614. National Project “Trams” (图论大YY)
- URAL 1614. National Project “Trams” (图论大YY)
- URAL1995-Illegal spices(贪心构造)
- 【构造】 URAL 1495 One-two, One-two 2
- 【构造】URAL 2004 Scientists from Spilkovo
- URAL 1995 Illegal spices 贪心构造
- URAL 1040 Airline Company 构造,思路 难度:2
- ural1979 Resources Distribution(构造)
- [构造 找规律 孔明棋] Ural 1051 Simple Game on a Grid
- URAL 1995 Illegal spices 贪心构造
- NWP National Writing Project’s value both in English and in Chinese
- Ural 2045 Richness of words(构造)
- URAL 1737 Mnemonics and Palindromes 3 构造
- URAL 1779 The Great Team 构造题
- 构造 Codeforces Round #Pi (Div. 2) B. Berland National Library
- Ural 2037. Richness of binary words 打表找规律 构造
- URAL 1549 Another Japanese Puzzle(构造)
- URAL 1032 A - Find a Multiple——抽屉原理+构造
- Illegal spices (URAL 1995 YY构造)