剑指offer19：按照从外向里以顺时针的顺序依次打印出每一个数字，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.

1 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.

2 思路和方法

　　直接定义一个矩形，在矩形的四条边取值，程序大大简化。

3 核心代码

 class Solution {
 public:
     vector<int> printMatrix(vector<vector<int> > matrix) {
         vector<int>vec;
         int row = matrix.size();
         int column = matrix[].size();
         int left = , right = column, up = , bottom = row;
         while((up < bottom) && (left < right))
         {
             for(int i = left; i < right; i++) vec.push_back(matrix[up][i]);
             for(int i = up+; i < bottom; i++) vec.push_back(matrix[i][right-]);
             for(int i = right--; ((bottom-)!=up)&&(i >=left); i--) vec.push_back(matrix[bottom-][i]);
             for(int i = bottom--; ((right-)!=left)&&(i >left); i--) vec.push_back(matrix[i][left]);
             up++;left++; right--; bottom--;
         }
         return vec;
     }
 };

4 完整代码

 #include<iostream>
 #include<vector>

 using namespace std;

 //直接定义一个矩形，在矩形的四条边取值，程序大大简化
 class Solution{
 public:
     vector<int>printMatrix(vector<vector<int>>  matrix) {
         vector<int>vec;
         int row = matrix.size();
         int column = matrix[].size();
         int left = , right = column, up = , bottom = row;
         while ((up < bottom) && (left < right))
         {
             for (int i = left; i < right; i++) vec.push_back(matrix[up][i]);
             for (int i = up + ; i < bottom; i++) vec.push_back(matrix[i][right - ]);
             for (int i = right -  - ; ((bottom - ) != up) && (i >= left); i--) vec.push_back(matrix[bottom - ][i]);
             for (int i = bottom -  - ; ((right - ) != left) && (i >left); i--) vec.push_back(matrix[i][left]);
             up++; left++; right--; bottom--;
         }
         return vec;
     }
 };

 int main()

 {
     Solution a;
     vector<vector<int>> matrix = { { , , , ,  }, { , , , ,  }, { , , , ,  } };//矩阵初始化
     vector<int> m = a.printMatrix(matrix);
     for (auto i : m)//依次打印返回矩阵的值
         cout << i << " ";
     cout << endl;

     return ;

 }

参考资料

https://blog.csdn.net/hangsyt108/article/details/80949337