【牛客网】顺时针打印矩阵

转载于牛客网

• 题目：
  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.

• 代码：

class Solution {
public:
    vector<int> printMatrix(vector<vector<int> > matrix) {
    vector<int>res;
    res.clear();
    int row = matrix.size();//行数
    int collum = matrix[0].size();//列数
    if (row == 0 || collum == 0)return res;
    /*
    int cricle = ((row < collum ? row : collum) - 1) / 2+1;//计算打印的圈数
    //对应偶数和奇数不同的情况，这种处理方式很妙，值得学习
    */
    int left = 0, top = 0, right = collum - 1, 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
        if (top != bottom)
        for (int i = right - 1; i >= left; --i)  res.push_back(matrix[bottom][i]);
        // bottom to top
        if (left != right)
        for (int i = bottom - 1; i > top; --i)  res.push_back(matrix[i][left]);
        left++, top++, right--, bottom--;
    }
    return res;
    }
};