Spiral Matrix

Problem

Given aNXN matrix, starting from the upper right corner of the matrix start printingvalues in a counter-clockwise fashion.
E.g.: Consider N = 4
Matrix= {a, b, c, d,
e, f, g, h,
i, j, k, l,
m, n, o, p}
Your function should output: dcbaeimnoplhgfjk

Solution

public ArrayList<Integer> spiralOrder(int[][] matrix) {
    ArrayList<Integer> res = new ArrayList<Integer>();
    
    if(matrix == null || matrix.length == 0) {
        return res;
    }
    
    int row = matrix.length;
    int col = matrix[0].length;
    
    int x = 0;
    int y = 0;
    while(row > 0 && col > 0) {
        //if row or col == 1, no circle can be found
        if(row == 1) {
            for(int i=0; i<col; i++) {
                res.add(matrix[x][y++]);
            }
            break;
        }
        if(col == 1) {
            for(int i=0; i<row; i++) {
                res.add(matrix[x++][y]);
            }
            break;
        }
        
        //row left to right
        for(int i=0; i<col-1; i++) {
            res.add(matrix[x][y++]);
        }
        //col high to low
        for(int i=0; i<row-1; i++) {
            res.add(matrix[x++][y]);
        }
        //row right to left
        for(int i=0; i<col-1; i++) {
            res.add(matrix[x][y--]);
        }
        //col low to high
        for(int i=0; i<row-1; i++) {
            res.add(matrix[x--][y]);
        }
        
        row = row - 2;
        col = col - 2;
        x++;
        y++;
        
    }
    
    return res;
}