顺时针打印矩阵

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.

问题分析

• 将问题分解，实现顺时针打印主要分几个步骤
• 对于判断条件和边界条件要仔细分析

解题思路1

class Solution {
public:
    vector<int> printMatrix(vector<vector<int> > matrix) {

        vector<int> printResult ;
        int rows = matrix.size();
        int cols = matrix[0].size();
        if(rows == 0 || cols == 0)
        {
            return printResult;
        }
        printResult.clear();
        int left = 0;
        int right = cols-1;
        int bottom = rows-1;
        int top = 0;
        //分解遍历
        while(left <= right && top <= bottom)
        {
            //自左到右
            for (int i = left; i <= right; ++i)
            {
                printResult.push_back(matrix[top][i]);
            }
            //自上到下
            for (int i = top+1; i <= bottom; ++i)
            {
                printResult.push_back(matrix[i][right]);
            }
            //自右向左,同时要判断left和right的大小
            if(bottom != top)
            {
                for (int i = right-1; i >= left; --i)
                {
                    printResult.push_back(matrix[bottom][i]);
                }
            }
            //自下向上,同时要判断bottom和top的大小
            if (right != left)
            {
                for(int i = bottom-1; i > top ; --i)
                {
                    printResult.push_back(matrix[i][left]);
                }
            }
            left++;
            top++;
            right--;
            bottom--;
        }
        return printResult;
    }
};