# 1864. Minimum Number of Swaps to Make the Binary String Alternating

https://leetcode.com/problems/minimum-number-of-swaps-to-make-the-binary-string-alternating

## Description

Given a binary string `s`, return _the **minimum** number of character swaps to make it **alternating**, or_ `-1` _if it is impossible._

The string is called **alternating** if no two adjacent characters are equal. For example, the strings `"010"` and `"1010"` are alternating, while the string `"0100"` is not.

Any two characters may be swapped, even if they are **not adjacent**.

**Example 1:**

```
**Input:** s = "111000"
**Output:** 1
**Explanation:** Swap positions 1 and 4: "111000" -> "101010"
The string is now alternating.
```

**Example 2:**

```
**Input:** s = "010"
**Output:** 0
**Explanation:** The string is already alternating, no swaps are needed.
```

**Example 3:**

```
**Input:** s = "1110"
**Output:** -1
```

**Constraints:**

* `1 <= s.length <= 1000`
* `s[i]` is either `'0'` or `'1'`.

## ac

```java
```
