题解 | #顺时针打印矩阵#

class Solution {
  public:
    vector<int> printMatrix(vector<vector<int> > matrix) {
        int i = 0, j = 0;
        vector<int> v;
        while (v.size() < matrix.size()*matrix[0].size()) {
            //右
            if (matrix[i][j] == -1) ++j;
            while (j < matrix[i].size() && matrix[i][j] != -1) {
                v.push_back(matrix[i][j]);
                matrix[i][j] = -1;
                ++j;
            }
            --j;
            //下
            if (matrix[i][j] == -1) ++i;
            while (i < matrix.size() && matrix[i][j] != -1) {
                v.push_back(matrix[i][j]);
                matrix[i][j] = -1;
                ++i;
            }
            --i;
            //左
            if (matrix[i][j] == -1) --j;
            while (j >= 0 && matrix[i][j] != -1) {
                v.push_back(matrix[i][j]);
                matrix[i][j] = -1;
                --j;
            }
            ++j;
            //上
            if (matrix[i][j] == -1) --i;
            while (i >= 0 && matrix[i][j] != -1) {
                v.push_back(matrix[i][j]);
                matrix[i][j] = -1;
                --i;
            }
            ++i;
        }
        return v;
    }
};