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Boundary traversal of matrix

Tags : matrix, geeksforgeeks, cpp, easy

Problem Statement - link #

You are given a matrix of dimensions n x m. The task is to perform boundary traversal on the matrix in a clockwise manner.

Your Task: Complete the function boundaryTraversal() that takes matrix, n and m as input parameters and returns the list of integers that form the boundary traversal of the matrix in a clockwise manner.

Expected Time Complexity: O(N+M)
Expected Auxiliary Space: O(1)

Examples #

Example 1:

Input:
n = 4, m = 4
matrix[][] = [[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
Explanation:
The matrix is:
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
The boundary traversal is:
1 2 3 4 8 12 16 15 14 13 9 5

Example 2:

Input:
n = 3, m = 4
matrrix[][] = [[12, 11, 10, 9], [8, 7, 6, 5], [4, 3, 2, 1]]
Output: 12 11 10 9 5 1 2 3 4 8

Constraints #

Solutions #

class Solution{
    public:
    //Function to return list of integers that form the boundary 
    //traversal of the matrix in a clockwise manner.
    vector<int> boundaryTraversal(vector<vector<int> > matrix, int n, int m) {
        // code here
        if(n==1) return matrix[0];
        vector<int> res;
        for(int i=0; i<m; i++) res.push_back(matrix[0][i]);
        for(int i=1; i<n; i++) res.push_back(matrix[i][m-1]);
        if(m!=1){
            for(int i=m-2; i>=0; i--) res.push_back(matrix[n-1][i]);
            for(int i=n-2; i>0; i--) res.push_back(matrix[i][0]);            
        }

        return res;
        
    }

};