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# 765. Couples Holding Hands

## Description

N couples sit in 2N seats arranged in a row and want to hold hands. We want to know the minimum number of swaps so that every couple is sitting side by side. A *swap* consists of choosing **any** two people, then they stand up and switch seats.

The people and seats are represented by an integer from `0`

to `2N-1`

, the couples are numbered in order, the first couple being `(0, 1)`

, the second couple being `(2, 3)`

, and so on with the last couple being `(2N-2, 2N-1)`

.

The couples' initial seating is given by `row[i]`

being the value of the person who is initially sitting in the i-th seat.

**Example 1:**

Input:row = [0, 2, 1, 3]Output:1Explanation:We only need to swap the second (row[1]) and third (row[2]) person.

**Example 2:**

Input:row = [3, 2, 0, 1]Output:0Explanation:All couples are already seated side by side.

**Note:**

`len(row)`

is even and in the range of`[4, 60]`

.`row`

is guaranteed to be a permutation of`0...len(row)-1`

.