题目描述
The Chef's latest idea is that some cooks might work better in pairs. So, he is going to experiment by pairing up some of his employees to see if the quality of the food prepared in his kitchen increases. However, only some pairs of employees are compatible. Two employees that are not compatible cannot be paired together.
For each pair of compatible employees, the Chef has assigned a number estimating how well the overall quality of the food might increase. Of course, each employee can only be paired with at most one other employee. Furthermore, it is ok to not pair some employees. So, your goal is to help the Chef decide how to pair the employees to maximize the total amount that the overall quality of food increases.
Input
The first line contains a single integer denoting the number of test cases (at most 50). Each test case begins with two integers n and m. Here, n is the number of employees (between 2 and 1000) and m is the number of compatible pairs of employees (between 1 and 10,000). The employees are numbered from 0 to n-1. The next m lines describe a pair of compatible employees, one per line. The i'th such line contains two distinct integers ui,vi between 0 and n-1. Strangely enough, the Chef estimates that picking the i'th pair ui,vi will increase the quality of food prepared in his kitchen by exactly 2^i.
No pair of employees will be given more than once in the input. That is, for distinct indices i and j, we do not have both ui = uj and vi = vj, nor do we have both ui = vj and vi = uj.
Output
The output for each test case consists of the indices of the pairs of employees that are used in a maximum total value pairing (the indices are between 0 and m-1). These indices should be given in increasing order with a single space between consecutive numbers. If there is more than one possible output, then any will do.
Example
Input:
2
4 5
0 1
1 2
2 3
1 3
3 0
4 3
0 1
2 3
2 1
Output:
1 4
2
输入格式
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输出格式
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