```go
package main

import (
	"bufio"
	"fmt"
	"os"
)

func abs64(x int64) int64 {
	if x < 0 {
		return -x
	}
	return x
}

func solvePattern(pos0, pos1 []int, n int) (int64, bool) {
	c0, c1 := len(pos0), len(pos1)
	start0 := (n + 1) / 2
	start1 := n / 2
	if c0 != start0 || c1 != start1 {
		return 0, false
	}
	var cost int64
	for i, p := range pos0 {
		target := 2*i + 1
		cost += abs64(int64(p - target))
	}
	return cost, true
}

func minSwaps(a []int, n int) int64 {
	var pos0, pos1 []int
	for i := 1; i <= n; i++ {
		if a[i-1]&1 == 0 {
			pos0 = append(pos0, i)
		} else {
			pos1 = append(pos1, i)
		}
	}

	diff := len(pos0) - len(pos1)
	if diff < -1 || diff > 1 {
		return -1
	}

	const INF int64 = 1<<62 - 1
	best := INF

	c1, ok1 := solvePattern(pos0, pos1, n)
	if ok1 {
		if c1 < best {
			best = c1
		}
	}
	c2, ok2 := solvePattern(pos1, pos0, n)
	if ok2 {
		if c2 < best {
			best = c2
		}
	}

	if best == INF {
		return -1
	}
	return best / 2
}

func main() {
	in := bufio.NewReader(os.Stdin)
	out := bufio.NewWriter(os.Stdout)
	defer out.Flush()

	var t int
	fmt.Fscan(in, &t)
	for ; t > 0; t-- {
		var n int
		fmt.Fscan(in, &n)
		a := make([]int, n)
		for i := 0; i < n; i++ {
			fmt.Fscan(in, &a[i])
		}
		fmt.Fprintln(out, minSwaps(a, n))
	}
}
```