# 59. Spiral Matrix II

#### Medium

***

Given a positive integer `n`, generate an `n x n` `matrix` filled with elements from `1` to `n2` in spiral order.

 

**Example 1:**

![](https://assets.leetcode.com/uploads/2020/11/13/spiraln.jpg)

```
Input: n = 3
Output: [[1,2,3],[8,9,4],[7,6,5]]
```

**Example 2:**

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

 

**Constraints:**

* `1 <= n <= 20`

```python
class Solution:
    def generateMatrix(self, n: int) -> List[List[int]]:
        matrix = []
        for i in range(n):
            temp = []
            for j in range(n):
                temp.append(0)
            matrix.append(temp)
        startRow , endRow = 0, n-1
        startCol, endCol = 0, n-1
        start = 1
        while startRow <= endRow and startCol <= endCol:
            # Right
            for index in range(startCol, endCol+1):
                matrix[startRow][index] = start
                start += 1
            startRow += 1
            # Down
            for index in range(startRow, endRow+1):
                matrix[index][endCol] = start
                start += 1
            endCol -= 1
            # Left
            for index in range(endCol, startCol-1, -1):
                matrix[endRow][index] = start
                start += 1
            endRow -= 1
            # Up
            for index in range(endRow, startRow-1, -1):
                matrix[index][startCol] = start
                start += 1
            startCol += 1
        return matrix
```