# 两数之和

<p>给你一个&nbsp;<code>n&nbsp;x n</code>&nbsp;的二进制网格&nbsp;<code>grid</code>，每一次操作中，你可以选择网格的&nbsp;<strong>相邻两行</strong>&nbsp;进行交换。</p>

<p>一个符合要求的网格需要满足主对角线以上的格子全部都是 <strong>0</strong>&nbsp;。</p>

<p>请你返回使网格满足要求的最少操作次数，如果无法使网格符合要求，请你返回 <strong>-1</strong>&nbsp;。</p>

<p>主对角线指的是从&nbsp;<code>(1, 1)</code>&nbsp;到&nbsp;<code>(n, n)</code>&nbsp;的这些格子。</p>

<p>&nbsp;</p>

<p><strong>示例 1：</strong></p>

<p><img alt="" src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2020/08/02/fw.jpg" style="height: 141px; width: 750px;"></p>

<pre><strong>输入：</strong>grid = [[0,0,1],[1,1,0],[1,0,0]]
<strong>输出：</strong>3
</pre>

<p><strong>示例 2：</strong></p>

<p><img alt="" src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2020/08/02/e2.jpg" style="height: 270px; width: 270px;"></p>

<pre><strong>输入：</strong>grid = [[0,1,1,0],[0,1,1,0],[0,1,1,0],[0,1,1,0]]
<strong>输出：</strong>-1
<strong>解释：</strong>所有行都是一样的，交换相邻行无法使网格符合要求。
</pre>

<p><strong>示例 3：</strong></p>

<p><img alt="" src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2020/08/02/e3.jpg" style="height: 210px; width: 210px;"></p>

<pre><strong>输入：</strong>grid = [[1,0,0],[1,1,0],[1,1,1]]
<strong>输出：</strong>0
</pre>

<p>&nbsp;</p>

<p><strong>提示：</strong></p>

<ul>
	<li><code>n == grid.length</code></li>
	<li><code>n == grid[i].length</code></li>
	<li><code>1 &lt;= n&nbsp;&lt;= 200</code></li>
	<li><code>grid[i][j]</code>&nbsp;要么是&nbsp;<code>0</code>&nbsp;要么是&nbsp;<code>1</code>&nbsp;。</li>
</ul>

<p>以下错误的选项是？</p>

## aop
### before
```cpp

```
### after
```cpp

```

## 答案
```cpp

```
## 选项

### A
```cpp

```

### B
```cpp

```

### C
```cpp

```
