面试题20 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.

class Solution {
public:
    void printCircle(vector<vector<int> > matrix, int start, vector<int> &v){
        int rows = matrix.size(), columns = matrix[0].size();
        int endx = columns - 1 - start;
        int endy = rows - 1 - start;
        for (int i = start; i <= endx; i++)
            v.push_back(matrix[start][i]);
        if (start < endy){
            for (int i = start + 1; i <= endy; i++)
                v.push_back(matrix[i][endx]);
        }
        if (start < endx && start < endy){
            for (int i = endx - 1; i >= start; i--)
                v.push_back(matrix[endy][i]);
        }
        if (start < endx && start < endy - 1){
            for (int i = endy - 1; i >= start + 1; i--){
                v.push_back(matrix[i][start]);
            }
        }
    }
    
    vector<int> printMatrix(vector<vector<int> > matrix) {
        vector<int> v;
        int rows = matrix.size(), columns = matrix[0].size();
        int start = 0;
        while (columns > start * 2 && rows > start * 2){
            printCircle(matrix, start, v);
            start++;
        }
        return v;
    }
};