Couples sit next to each other
All submissions for this problem are available.
Read problems statements in Mandarin chinese, Russian and Vietnamese as well.
There are N couples numbered 1 through N. Each couple consists of two people. There are also 2N chairs numbered 1 through 2N. Each chair has a person sitting on it; for each i (1 ≤ i ≤ 2N), the person initially sitting on chair i belongs to couple number Ai. The chairs are placed in a circle, so chairs i and i+1 are adjacent for each 1 ≤ i ≤ 2N-1; chairs 2N and 1 are also adjacent.
You may perform the following operation any number of times (including zero): choose two people sitting on adjacent chairs and swap them.
We would like all couples to sit on adjacent chairs. Compute the minimum number of operations needed to achieve this.
- The first line of the input contains a single integer T denoting the number of test cases. The description of T test cases follows.
- The first line of each test case contains a single integer N.
- The second line contains 2N space-separated integers A1, A2, ..., A2N.
For each test case, print a single line containing one number — the minimum number of operations required to make each couple sit next to each other.
- 1 ≤ T ≤ 1,000
- 1 ≤ N ≤ 500,000
- 1 ≤ sum of N over all test cases ≤ 1,000,000
- 1 ≤ Ai ≤ N for each valid i
- each number from 1 to N appears in A exactly twice
Subtask #1 (35 points):
- N ≤ 1,000
- sum of N over all test cases ≤ 5,000
Subtask #2 (65 points): original constraints
Input: 2 2 1 2 1 2 3 1 2 3 1 3 2 Output: 1 2
|Tags||kingofnumbers, ltime57, med-hard, segment-tree|
|Time Limit:||2 sec|
|Source Limit:||50000 Bytes|
|Languages:||C, CPP14, JAVA, PYTH, PYTH 3.5, PYPY, CS2, PAS fpc, PAS gpc, RUBY, PHP, GO, NODEJS, HASK, rust, SCALA, swift, D, PERL, FORT, WSPC, ADA, CAML, ICK, BF, ASM, CLPS, PRLG, ICON, SCM qobi, PIKE, ST, NICE, LUA, BASH, NEM, LISP sbcl, LISP clisp, SCM guile, JS, ERL, TCL, kotlin, PERL6, TEXT, SCM chicken, CLOJ, COB, FS|
Fetching successful submissions
If you are still having problems, see a sample solution here.