To prove safety offer- face questions 29- clockwise print matrix - Matrix

/*
topic:
	Enter a matrix, in order from outside to inside of a clockwise turn each digital printing.
*/
/*
Ideas:
	1, the printing matrix is ​​considered as a print from the outside of the ring.
	2, each ring has a start node, coordinates of the starting node * 2 less than the number of rows and columns.
	3, for each ring, each printed from left to right, top to bottom, right to left, from the bottom to the figures.
*/
#include<iostream>
#include<string.h>
#include<algorithm>
#include<cmath>
#include<stdio.h>
#include<vector>

using namespace std;
// res pass by reference
void printMatrixs(vector<vector<int> > mat,int rows,int columns,int start,vector<int> &res){
    int right = columns - start;
    int down = rows -start;

    // print a line from left to right
    for(int i = start; i < right; i++){
        res.push_back(mat[start][i]);
    }
    // print one from top to bottom
    for(int i = start + 1; i < down; i++){
        res.push_back(mat[i][right-1]);
    }
    // print a line from right to left, not left and right to print duplicate lines
    if(down - 1 != start){
         for(int i = right - 2; i >= start; i--){
            res.push_back(mat[down-1][i]);
        }
    }

    // print from a lower to a not printed upside down and repeating the column
    if(start != right - 1){
        for(int i = down - 2; i > start; i--){
            res.push_back(mat[i][start]);
        }
    }

}

vector<int> clockwisePrint(vector<vector<int>> mat, int rows, int columns) {
    if(rows == 0 || columns == 0) throw("invalid parameters");
    int start = 0;
    vector<int> res;
    while(start*2 < rows && start*2 <columns){
        printMatrixs(mat,rows,columns,start,res);
        start++;
    }
    return res;
}



int main () {
   vector<vector<int>> mat = {{1,2,3,4},{5,6,7,8},{9,10,11,12},{13,14,15,16}};
   vector<int> res = clockwisePrint(mat,4,4);
   for(int i = 0; i < res.size(); i++){
    cout<<res[i]<<" ";
   }
}