54. Spiral Matrix.cpp

Given an m x n matrix, return all elements of the matrix in spiral order.

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

Example 2:
Input: matrix = [[1,2,3,4],
				 [5,6,7,8],
				 [9,10,11,12]]
Output: [1,2,3,4,8,12,11,10,9,5,6,7]
 
Constraints:
m == matrix.length
n == matrix[i].length
1 <= m, n <= 10
-100 <= matrix[i][j] <= 100
********************************************************************************










# Approach 1: CLockwise Spiral

class Solution {
public:
    vector<int> spiralOrder(vector<vector<int>>& matrix) {
        vector<int> res;

        int m = matrix.size(), n = matrix[0].size();
        int r = 0, c = 0;

        while (r < m && c < n) {
            for (int i = c; i < n; i++) res.push_back(matrix[r][i]);
            r++;

            for (int i = r; i < m; i++) res.push_back(matrix[i][n - 1]);
            n--;

            if (r >= m || c >= n) break;

            for (int i = n - 1; i >= c; i--) res.push_back(matrix[m - 1][i]);
            m--;

            for (int i = m - 1; i >= r; i--) res.push_back(matrix[i][c]);
            c++;
        }
        
        return res;
    }
};

TC -> O(m * n), m, n is the size of the matrix
SC -> O(1)
********************************************************************************










# Approach 2: Counter Clockwise Spiral (Not asked in the above problem)

class Solution {
public:
    vector<int> spiralOrder(vector<vector<int>>& matrix) {
        vector<int> res;

        int m = matrix.size(), n = matrix[0].size();
        int r = 0, c = 0;

        while (r < m && c < n) {
            for (int i = r; i < m; i++) res.push_back(matrix[i][c]);
            c++;

            for (int i = c; i < n; i++) res.push_back(matrix[m - 1][i]);
            m--;

            if (r >= m || c >= n) break;

            for (int i = m - 1; i >= r; i--) res.push_back(matrix[i][n - 1]);
            n--;

            for (int i = n - 1; i >= c; i--) res.push_back(matrix[r][i]);
            r++;
        }
        
        return res;
    }
};

TC -> O(m * n), m, n is the size of the matrix
SC -> O(1)