Spiral Matrix II Leetcode Solution

In this post, you will know how to solve the Spiral Matrix II Leetcode Solution problem of Leetcode. This Leetcode problem is done in many programming languages like C++, Java, and Python.

Spiral Matrix II Leetcode Solution
Spiral Matrix II Leetcode Solutions

One more thing to add, don’t directly look for the solutions, first try to solve the problems of Leetcode by yourself. If you find any difficulty after trying several times, then you can look for solutions.

Problem

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

Example 1:

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

Example 2:

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

Constraints:

  • 1 <= n <= 20

Spiral Matrix II Leetcode Solutions in Python

class Solution:
  def generateMatrix(self, n: int) -> List[List[int]]:
    ans = [[0] * n for _ in range(n)]
    count = 1
    for min in range(n // 2):
      max = n - min - 1
      for i in range(min, max):
        ans[min][i] = count
        count += 1
      for i in range(min, max):
        ans[i][max] = count
        count += 1
      for i in range(max, min, -1):
        ans[max][i] = count
        count += 1
      for i in range(max, min, -1):
        ans[i][min] = count
        count += 1
    if n & 1:
      ans[n // 2][n // 2] = count
    return ans

Spiral Matrix II Leetcode Solutions in CPP

class Solution {
 public:
  vector<vector<int>> generateMatrix(int n) {
    vector<vector<int>> ans(n, vector<int>(n));
    int count = 1;
    for (int min = 0; min < n / 2; ++min) {
      const int max = n - min - 1;
      for (int i = min; i < max; ++i)
        ans[min][i] = count++;
      for (int i = min; i < max; ++i)
        ans[i][max] = count++;
      for (int i = max; i > min; --i)
        ans[max][i] = count++;
      for (int i = max; i > min; --i)
        ans[i][min] = count++;
    }
    if (n & 1)
      ans[n / 2][n / 2] = count;
    return ans;
  }
};

Spiral Matrix II Leetcode Solutions in Java

class Solution {
  public int[][] generateMatrix(int n) {
    int[][] ans = new int[n][n];
    int count = 1;
    for (int min = 0; min < n / 2; ++min) {
      final int max = n - min - 1;
      for (int i = min; i < max; ++i)
        ans[min][i] = count++;
      for (int i = min; i < max; ++i)
        ans[i][max] = count++;
      for (int i = max; i > min; --i)
        ans[max][i] = count++;
      for (int i = max; i > min; --i)
        ans[i][min] = count++;
    }
    if (n % 2 == 1)
      ans[n / 2][n / 2] = count;
    return ans;
  }
}

Note: This problem Spiral Matrix II is generated by Leetcode but the solution is provided by  BrokenProgrammers. This tutorial is only for Educational and Learning purposes.

Next: Permutation Sequence Leetcode Solution

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