class Solution {
public:
    vector<int> printMatrix(vector<vector<int> > matrix) {
        vector<int>ans; ans.clear();
        int c, r = matrix.size();
        if (r != 0) c = matrix[0].size();
        else return ans;
        vector<vector<bool> >bord(r, vector<bool>(c, false));
        if (r * c == 0) return ans;
        int count = 1;
        int flag = 0;
        int xpos = 0, ypos = 0;
        ans.push_back(matrix[0][0]); bord[0][0] = true;
        while (count != r * c) {
            switch (flag) {
                case 0:while(ypos + 1 < c && !bord[xpos][ypos + 1]){count++;ans.push_back(matrix[xpos][++ ypos]);bord[xpos][ypos] = true;}break;
                case 1:while(xpos + 1 < r && !bord[xpos + 1][ypos]){count++;ans.push_back(matrix[++ xpos][ypos]);bord[xpos][ypos] = true;}break;
                case 2:while(ypos - 1 >= 0 && !bord[xpos][ypos - 1]){count++;ans.push_back(matrix[xpos][ --ypos]);bord[xpos][ypos] = true;}break;
                case 3:while(xpos - 1 >= 0 && !bord[xpos - 1][ypos]){count++;ans.push_back(matrix[-- xpos][ypos]);bord[xpos][ypos] = true;}break;
            }
            flag ++; flag %= 4;
        }
        return ans;
    }
};