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# Pascal's Triangle

## Description

Given a non-negative integer *numRows*, generate the first *numRows* of Pascal's triangle.

![](https://upload.wikimedia.org/wikipedia/commons/0/0d/PascalTriangleAnimated2.gif)\
In Pascal's triangle, each number is the sum of the two numbers directly above it.

**Example:**

```
Input: 5
Output:
[
     [1],
    [1,1],
   [1,2,1],
  [1,3,3,1],
 [1,4,6,4,1]
]
```

## Solution

```cpp
class Solution {
public:
    vector<vector<int>> generate(int numRows) {
        vector<vector<int>> ans(numRows);
        if(numRows == 0) return ans;
        ans[0].push_back(1);
        for(int i = 1; i < numRows; ++i){
            ans[i].push_back(1);
            for(int j = 1; j < i; ++j){
                ans[i].push_back(ans[i - 1][j - 1] + ans[i - 1][j]);
            }
            ans[i].push_back(1);
        }
        return ans;
    }
};
```