Description
There are n couples sitting in 2n seats arranged in a row. Return the minimum number of swaps so that every couple is sitting side by side.
Examples
Input:
row = [0,2,1,3]Output:
1Explanation:
Swap row[1] and row[2].
Input:
row = [3,2,0,1]Output:
0Explanation:
Couple (2,3) sits in seats 0-1 as [3,2], and couple (0,1) sits in seats 2-3 as [0,1]. Both couples are already adjacent, requiring 0 swaps.
Input:
row = [5,4,3,2,1,0]Output:
3Explanation:
Three swaps are needed to seat each couple side by side.
Constraints
- •
2n == row.length - •
2 ≤ n ≤ 30 - •
0 ≤ row[i] < 2n