D31_Spirally_traversing_a_matrix.cpp

// You are given a rectangular matrix mat[][] of size n x m, and your task is to return an array while traversing the matrix in spiral form.

// Examples:

// Input: mat[][] = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]
// Output: [1, 2, 3, 4, 8, 12, 16, 15, 14, 13, 9, 5, 6, 7, 11, 10]
// Explanation: 

// Input: mat[][] = [[1, 2, 3, 4, 5, 6], [7, 8, 9, 10, 11, 12], [13, 14, 15, 16, 17, 18]]
// Output: [1, 2, 3, 4, 5, 6, 12, 18, 17, 16, 15, 14, 13, 7, 8, 9, 10, 11]
// Explanation: Applying same technique as shown above.
// Input: mat[][] = [[32, 44, 27, 23], [54, 28, 50, 62]]
// Output: [32, 44, 27, 23, 62, 50, 28, 54]
// Explanation: Applying same technique as shown above, output will be [32, 44, 27, 23, 62, 50, 28, 54].



class Solution {
public:
    vector<int> spirallyTraverse(vector<vector<int>> &mat) {
        vector<int> result;
        
        int top = 0, bottom = mat.size() - 1;
        int left = 0, right = mat[0].size() - 1;
        
        while (top <= bottom && left <= right) {
            // Traverse from left to right across the top row
            for (int i = left; i <= right; ++i) {
                result.push_back(mat[top][i]);
            }
            top++;  // Move the top boundary downwards
            
            // Traverse from top to bottom along the right column
            for (int i = top; i <= bottom; ++i) {
                result.push_back(mat[i][right]);
            }
            right--;  // Move the right boundary to the left
            
            if (top <= bottom) {
                // Traverse from right to left across the bottom row
                for (int i = right; i >= left; --i) {
                    result.push_back(mat[bottom][i]);
                }
                bottom--;  // Move the bottom boundary upwards
            }
            
            if (left <= right) {
                // Traverse from bottom to top along the left column
                for (int i = bottom; i >= top; --i) {
                    result.push_back(mat[i][left]);
                }
                left++;  // Move the left boundary to the right
            }
        }
        
        return result;
    }
};