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[0].size();
        int left = 0, right = column, up = 0, bottom = row;
        while((up < bottom) && (left < right))
        {
            for(int i = left; i < right; i++) vec.push_back(matrix[up][i]);
            for(int i = up+1; i < bottom; i++) vec.push_back(matrix[i][right-1]);
            for(int i = right-1-1; ((bottom-1)!=up)&&(i >=left); i--) vec.push_back(matrix[bottom-1][i]);
            for(int i = bottom-1-1; ((right-1)!=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[0].size();
        int left = 0, right = column, up = 0, bottom = row;
        while ((up < bottom) && (left < right))
        {
            for (int i = left; i < right; i++) vec.push_back(matrix[up][i]);
            for (int i = up + 1; i < bottom; i++) vec.push_back(matrix[i][right - 1]);
            for (int i = right - 1 - 1; ((bottom - 1) != up) && (i >= left); i--) vec.push_back(matrix[bottom - 1][i]);
            for (int i = bottom - 1 - 1; ((right - 1) != left) && (i >left); i--) vec.push_back(matrix[i][left]);
            up++; left++; right--; bottom--;
        }
        return vec;
    }
};

int main()

{
    Solution a;
    vector<vector<int>> matrix = { { 1, 2, 3, 4, 5 }, { 6, 7, 8, 9, 10 }, { 11, 12, 13, 14, 15 } };//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 0;

}

参考资料

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