Road Demolishing

4.8

5 votes
Algorithms, Approved, Graphs, Hard, Open
Problem

King Tle4Ever just appointed Moron as the new Engineer for his country Time Limit Exceeded. In the country of Time Limit Exceeded there are n cities and there is a direct road between each pair of cities. Now cleaning up these roads costs Tle4Ever a lot of money so he wants to demolish some of the roads but not all for sure. He wants to demolish these roads in such a way that if he picks any subset of size q of these cities, than in this subset there should exist at least one pair of cities that doesn't have a direct road between them.

He asks Moron to come up with a demolishing plan satisfying his conditions. Now, as Moron is not good at coming up with plans, he asks you to help him. Now as coming up with such a plan is really difficult, given n and q you have to tell minimum number of roads that you have to demolish to satisfy King's condition.

For example : Suppose there are 4 cities. Total number of roads in the country are 6. Suppose king chooses q as 3. Than you have to demolish at least 2 roads to satisfy King's condition. If you demolish only 1 road than there will be at least one subset of size 3 which will have road between all pair of cities. Of course you can demolish more than 2 roads but the minimum number of roads that you have to demolish are 2.

[Input]
First line of input contains a single integer t denoting number of test cases.
Next t lines contains 2 integers n and q each.

[Output]
For each test case output the minimum number of roads that you have to demolish.

[Constraints]
1<=t<=105
3<=n<=106
3<=q<=n

Time Limit: 1
Memory Limit: 256
Source Limit:
Explanation

For case 1 : Explanation as in question.

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