# 杨辉三角

<p>给定一个非负整数 <em><code>numRows</code>，</em>生成「杨辉三角」的前 <em><code>numRows</code> </em>行。</p>

<p><small>在「杨辉三角」中，每个数是它左上方和右上方的数的和。</small></p>

<p><img alt="" src="https://img-service.csdnimg.cn/img_convert/53cb4e7f630b8a991ebd02133e79a9c8.gif" /></p>

<p> </p>

<p><strong>示例 1:</strong></p>

<pre>
<strong>输入:</strong> numRows = 5
<strong>输出:</strong> [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]
</pre>

<p><strong>示例 2:</strong></p>

<pre>
<strong>输入:</strong> numRows = 1
<strong>输出:</strong> [[1]]
</pre>

<p> </p>

<p><strong>提示:</strong></p>

<ul>
	<li><code>1 <= numRows <= 30</code></li>
</ul>


## template

```java
class Solution {
	public List<List<Integer>> generate(int numRows) {
		List<List<Integer>> res = new ArrayList<List<Integer>>();
		if (numRows == 0) {
			return res;
		}
		for (int i = 0; i < numRows; ++i) {
			List<Integer> temp = new ArrayList<Integer>();
			for (int j = 0; j <= i; ++j) {
				temp.add(numberget(i, j));
			}
			res.add(temp);
		}
		return res;
	}

	public int numberget(int i, int j) {
		if (j == 0 || i == j) {
			return 1;
		} else {
			return (numberget(i - 1, j - 1) + numberget(i - 1, j));
		}
	}
}
```

## 答案

```java

```

## 选项

### A

```java

```

### B

```java

```

### C

```java

```