## Algorithm

Problem Nmae: 118. Pascal's Triangle

Given an integer `numRows`, return the first numRows of Pascal's triangle.

In Pascal's triangle, each number is the sum of the two numbers directly above it as shown:

Example 1:

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

Example 2:

```Input: numRows = 1
Output: [[1]]
```

Constraints:

• `1 <= numRows <= 30`

## Code Examples

### #1 Code Example with C Programming

```Code - C Programming```

``````
int** generate(int numRows, int** columnSizes) {
int i, j;
int *buff, **p;
p = malloc(numRows * sizeof(int *));
*columnSizes = malloc(numRows * sizeof(int));
//assert(p && *columnSizes);
for (i = 1; i  < = numRows; i ++) {
buff = malloc(i * sizeof(int));
//assert(buff);
p[i - 1] = buff;
(*columnSizes)[i - 1] = i;
buff[0] = 1;
for (j = 1; j  <  i - 1; j ++) {
buff[j] = p[i - 2][j - 1] + p[i - 2][j];
}
buff[i - 1] = 1;
}
return p;
}
``````
Copy The Code &

Input

cmd
numRows = 5

Output

cmd
[[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]

### #2 Code Example with C++ Programming

```Code - C++ Programming```

``````
class Solution {
public:
vector<vector<int>> generate(int numRows) {
if(numRows == 0) return {};
if(numRows == 1) return {{1}};
auto v = generate(numRows - 1);
auto lastRow = *(v.end() - 1);
vector<int>res(1, 1);
for(int i = 0; i < lastRow.size() - 1; i++) res.push_back(lastRow[i] + lastRow[i + 1]);
res.push_back(1);
v.push_back(res>;
return v;
}
};
``````
Copy The Code &

Input

cmd
numRows = 5

Output

cmd
[[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]

### #3 Code Example with Java Programming

```Code - Java Programming```

``````
class Solution {
public List();
for (int i = 0; i  <  numRows; i++) {
List temp = new ArrayList<>();
for (int j = 0; j  < = i; j++) {
(j == 0 || j == i) ? 1 :
(result.get(i - 1).get(j - 1) + result.get(i - 1).get(j)));
}
}
return result;
}
}
``````
Copy The Code &

Input

cmd
numRows = 1

Output

cmd
[[1]]

### #4 Code Example with Javascript Programming

```Code - Javascript Programming```

``````
const generate = function(numRows) {
// row 0 => [1] length 0
// row 1 => [1, 1] length 1
// row 2 => [1, 2, 1] length 2
// row 3 => [1, 3, 3, 1] length 3

// current[i] = prev[i - 1] + prev[i]

const res = [];
for (let row = 0; row  <  numRows; row += 1) {
if (row === 0) {
res.push([1]);
continue;
}

if (row === 1) {
res.push([1, 1]);
continue;
}

const newRow = [];
const maxIdx = row;
for (let i = 0; i  < = maxIdx; i += 1) {
if (i === 0 || i === maxIdx) {
newRow.push(1);
} else {
newRow.push(res[row - 1][i - 1] + res[row - 1][i]);
}
}
res.push(newRow);
}

return res;
};
``````
Copy The Code &

Input

cmd
numRows = 1

Output

cmd
[[1]]

### #5 Code Example with Python Programming

```Code - Python Programming```

``````
class Solution:
def generate(self, numRows: int) -> List[List[int]]:
res = numRows and [[1]] or []
for _ in range(numRows-1):
res.append([1] + [a + b for a, b in zip(res[-1], res[-1][1:])] + [1])
return res
``````
Copy The Code &

Input

cmd
numRows = 5

Output

cmd
[[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]

### #6 Code Example with C# Programming

```Code - C# Programming```

``````
using System.Collections.Generic;

namespace LeetCode
{
public class _118_PascalsTriangle
{
public IList < IList<int>> Generate(int numRows)
{
var results = new List < IList<int>>();
if (numRows  < = 0) return results;
if (numRows == 1) return results;
results.Add(new List < int>(2) { 1, 1 });
if (numRows == 2) return results;

for (int i = 2; i  <  numRows; i++)
{
var result = new List<int>(i + 1);
for (int j = 1; j  <  i; j++)
{
result.Add(results[i - 1][j - 1] + results[i - 1][j]);
}
}
return results;
}
}
}
``````
Copy The Code &

Input

cmd
numRows = 5

Output

cmd
[[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]