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3687：Labeling Balls

题目描述

Windy has N balls of distinct weights from 1 unit to N units. Now he tries to label them with 1 to N in such a way that:

  1. No two balls share the same label.
  2. The labeling satisfies several constrains like "The ball labeled with a is lighter than the one labeled with b".

Can you help windy to find a solution?

输入解释

The first line of input is the number of test case. The first line of each test case contains two integers, N (1 ≤ N ≤ 200) and M (0 ≤ M ≤ 40,000). The next M line each contain two integers a and b indicating the ball labeled with a must be lighter than the one labeled with b. (1 ≤ a, b ≤ N) There is a blank line before each test case.

输出解释

For each test case output on a single line the balls' weights from label 1 to label N. If several solutions exist, you should output the one with the smallest weight for label 1, then with the smallest weight for label 2, then with the smallest weight for label 3 and so on... If no solution exists, output -1 instead.

输入样例 
5

4 0

4 1
1 1

4 2
1 2
2 1

4 1
2 1

4 1
3 2
输出样例 
1 2 3 4
-1
-1
2 1 3 4
1 3 2 4
该题目是Virtual Judge题目，来自 北京大学POJ
题目来源 POJ Founder Monthly Contest – 2008.08.31, windy7926778
源链接： POJ-3687
最后修改于 2020-10-29T07:08:12+00:00 由爬虫自动更新
共提交 0 次
通过率 --%
时间上限 内存上限
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