Codeforces Round 918 (Div. 4) |
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Finished |
There are $$$n$$$ people on the number line; the $$$i$$$-th person is at point $$$a_i$$$ and wants to go to point $$$b_i$$$. For each person, $$$a_i < b_i$$$, and the starting and ending points of all people are distinct. (That is, all of the $$$2n$$$ numbers $$$a_1, a_2, \dots, a_n, b_1, b_2, \dots, b_n$$$ are distinct.)
All the people will start moving simultaneously at a speed of $$$1$$$ unit per second until they reach their final point $$$b_i$$$. When two people meet at the same point, they will greet each other once. How many greetings will there be?
Note that a person can still greet other people even if they have reached their final point.
The first line of the input contains a single integer $$$t$$$ ($$$1 \le t \le 10^4$$$) — the number of test cases. The description of test cases follows.
The first line of each test case contains a single integer $$$n$$$ ($$$1 \le n \le 2 \cdot 10^5$$$) — the number of people.
Then $$$n$$$ lines follow, the $$$i$$$-th of which contains two integers $$$a_i$$$ and $$$b_i$$$ ($$$-10^9 \leq a_i < b_i \leq 10^9$$$) — the starting and ending positions of each person.
For each test case, all of the $$$2n$$$ numbers $$$a_1, a_2, \dots, a_n, b_1, b_2, \dots, b_n$$$ are distinct.
The sum of $$$n$$$ over all test cases does not exceed $$$2 \cdot 10^5$$$.
For each test case, output a single integer denoting the number of greetings that will happen.
522 31 462 63 94 51 87 10-2 1004-10 10-5 5-12 12-13 135-4 9-2 53 46 78 1041 23 45 67 8
1 9 6 4 0
In the first test case, the two people will meet at point $$$3$$$ and greet each other.
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