765. Couples Holding Hands

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: 1
Explanation: We only need to swap the second (row) and third (row) person.
```

Example 2:

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

Note:

1. `len(row)` is even and in the range of `[4, 60]`.
2. `row` is guaranteed to be a permutation of `0...len(row)-1`.

765. Couples Holding Hands
``````struct Solution;

impl Solution {
fn min_swaps_couples(mut row: Vec<i32>) -> i32 {
let n = row.len();
let mut res = 0;
for i in 0..n {
if i % 2 == 1 {
continue;
}
if row[i] == row[i + 1] ^ 1 {
continue;
}
res += 1;
for j in i + 2..n {
if row[i] == row[j] ^ 1 {
row.swap(i + 1, j);
break;
}
}
}
res
}
}

#[test]
fn test() {
let row = vec![0, 2, 1, 3];
let res = 1;
assert_eq!(Solution::min_swaps_couples(row), res);
let row = vec![3, 2, 0, 1];
let res = 0;
assert_eq!(Solution::min_swaps_couples(row), res);
}
``````