Matrix spiral copy - code review, readable variables, good idea to learn from the peer.

MatrixSpiralCopy_Codereview_myreview.cpp

#include <iostream>
#include <vector>

using namespace std;
/*
  1. right (up = 0),  down (right = n-1), left, up
  
  O(m*n), space = O(1)
  [[1]]
*/


vector<int> spiralCopy( const vector<vector<int>>& inputMatrix ) 
{
  // your code goes here
  if(inputMatrix.size() == 0)
    return {};
  
  int m = inputMatrix.size();
  int n = inputMatrix[0].size();
  
  int top = 0, right = n, left = -1, bottom = m;
  
  vector<int> result;
  
  int i = 0;
  int j = 0;
  
  int count = 0;
  int turn = 0; // 0, 1, 2, 3 - each for direction right, down, left, up
  
  while(count < m * n){
    if(turn == 0)
    { // Right
      result.push_back(inputMatrix[i][j++]);
      if(j == right){
        --j;
        ++i;
        turn = 1;
        right--;
      }
      count++;
    }
    else if(turn == 1){ // Down
      result.push_back(inputMatrix[i++][j]);
      count++;
      if(i==bottom){
        --i;
        --j;
        turn = 2;
        bottom--;
      }
    }
    else if(turn == 2){ // Left
      result.push_back(inputMatrix[i][j--]);
      count++;
      if(j==left){
        ++j;
        --i;
        turn = 3;
        left++;
      }
    }
    else if(turn == 3){ // Up
      result.push_back(inputMatrix[i--][j]);
      count++;
      if(i==top){
        ++i;
        ++j;
        turn = 0;
        top++;
      }
    }
  }
  
  return result;
}

int main() {
  vector<vector<int>> vec = { {}};  // two edges: empty, one element 
  
  vector<int> result = spiralCopy(vec);
  
  for(auto a : result){
    cout<<a<<endl;
  }
  return 0;
}