剑指offer 顺时针打印矩阵

输入一个矩阵，按照从外向里以顺时针的顺序依次打印出每一个数字，例如，如果输入如下4 X 4矩阵： 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 则依次打印出数字1,2,3,4,8,12,16,15,14,13,9,5,6,7,11,10.

class Solution {
public:
    vector<int> ans;
    int row,col;
    vector<int> printMatrix(vector<vector<int> > matrix) {
        
        row = matrix.size();
        col = matrix[0].size();
        int top = 0, bottom = row-1,left = 0,right = col-1;
        while(top <= bottom && left <= right){
            for(int i = left; i <= right; i++)
                ans.push_back(matrix[top][i]);
            for(int i = top+1; i <= bottom; i++)
                ans.push_back(matrix[i][right]);
            if(top < bottom)
                for(int i = right-1; i >= left; i--)
                    ans.push_back(matrix[bottom][i]);
            if(left < right)
                for(int i = bottom-1; i > top; i--)
                    ans.push_back(matrix[i][left]);
            left++,right--,top++,bottom--;
        }
        return ans;
    }
    
};