题目描述

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.
思路：用左上和右下的座标定位出一次要旋转打印的数据，一次旋转打印结束后，往对角分别前进和后退一个单位

class Solution {
public:
    vector<int> printMatrix(vector<vector<int> > matrix) {
        int row = matrix.size(); //定义行数
        int col = matrix[0].size();  //定义列数
        vector<int> res;
        if(row == 0 || col == 0)
            return res; //返回空数组
        int left = 0, right = col - 1, top = 0, bottom = row - 1;
        while(left <= right && top <= bottom){
            // left to right
            for(int i = left; i <= right; i++)
                res.push_back(matrix[top][i]);
            //top to bottom
            for(int i = top+1; i <= bottom; i++)
                res.push_back(matrix[i][right]);
            //right to left
            for(int i = right - 1; i >= left && top < bottom; i--)
                res.push_back(matrix[bottom][i]);
            //bottom to top
            for(int i = bottom - 1; i > top && right > left; i--)
                res.push_back(matrix[i][left]);
            left++; right--; top++; bottom--;
        }
        return res;
    }
};