19、剑指offer--顺时针打印链表

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.

 

解题思路：首先获得矩阵的行数和列数

1）然后定义四个变量表示当前的left、right、top、bottom

2）left<=right && top<=bottom按照从左到右、从上到下、从右到左、从下到上的顺序打印

3）需要注意的是：在从右到左时，如果当前矩阵只剩下一列，不需要进行此次操作，进行相关情况的判断；同理从下到上也是如此。

#include <iostream>
#include <vector>
using namespace std;
class Solution {
public:
    vector<int> printMatrix(vector<vector<int> > matrix) {
        vector<int> result;//存储结果
        int row = matrix.size();
        int colunm = matrix[0].size();
        if(row<=0 || colunm <= 0)
            return result;
        int left = 0;
        int right = colunm - 1;
        int top = 0;
        int bottom = row - 1;
        while((left<=right) && (top <= bottom))
        {
            //从左向右
            for(int i=left;i<=right;i++)
            {
                result.push_back(matrix[top][i]);
            }
            top++;
            //从上到下
            for(int i= top;i<=bottom;i++)
            {
                result.push_back(matrix[i][right]);
            }
            right--;
            //从右到左
            //只剩下一行情况，因为之前top已经++，此时top==bottom+1 但是left!=right，不加判断会又从右往回输出一遍
            if(top <= bottom)
            {
                for(int i =right;i>=left;i--)
                {
                    result.push_back(matrix[bottom][i]);
                }
            }
            bottom--;
            //从下到上
            //只剩下一列情况，此时top!=bottom 因为right之前已经--，此时left==right+1，不加判断会又从下往上再输出一遍
            if(left <= right)
            {
                for(int i= bottom;i>=top;i--)
                {
                    result.push_back(matrix[i][left]);
                }
            }
            left++;
        }
        return result;
    }
};
int main()
{
    vector<vector<int> > a;
    vector<int> b;
    b.push_back(1);
    b.push_back(2);
    b.push_back(3);
    b.push_back(4);
    a.push_back(b);
    b.clear();
    b.push_back(5);
    b.push_back(6);
    b.push_back(7);
    b.push_back(8);
    a.push_back(b);
    b.clear();
    b.push_back(9);
    b.push_back(10);
    b.push_back(11);
    b.push_back(12);
    a.push_back(b);
    b.clear();
    b.push_back(13);
    b.push_back(14);
    b.push_back(15);
    b.push_back(16);
    a.push_back(b);
    b.clear();
    Solution s;
    vector<int> c;
    c = s.printMatrix(a);
    for(int i=0;i<c.size();i++)
        cout<<c[i]<<"  ";
    cout<<endl;

    b.clear();
    a.clear();
    b.push_back(1);
    b.push_back(2);
    b.push_back(3);
    b.push_back(4);
    b.push_back(5);
    a.push_back(b);

    c = s.printMatrix(a);
    for(int i=0;i<c.size();i++)
        cout<<c[i]<<"  ";
    cout<<endl;
    return 0;
}