snakeMatrix.cpp

#include <iostream>
#include <string>
#include <vector>
#include <stack>
#include <sstream>
#include <utility>
using namespace std;

void getNextPoint(pair<int, int> &point, int m , int n, int &dir) {
  int x = point.first;
  int y = point.second;
  if (dir == 1) {  
    if (y == n - 1) {
      point.first++;
      dir = -1;
    } else if (x == 0) {
      point.second++;
      dir = -1;
    } else {
      point.first--;
      point.second++;
    }
  } else {
    if (x == m - 1) {
      point.second++;
      dir = 1;
    } else if (y == 0) {
      point.first++;
      dir = 1;
    } else {
      point.first++;
      point.second--;
    }
  }
}

vector<vector<int> > snakeMatrix(int m, int n) {
  vector<vector<int> > matrix(m, vector<int>(n));
  pair<int, int> point(0, 0);
  int dir = 1;
  for (int i = 0; i < m * n; i++) {
    matrix[point.first][point.second] = i + 1;
    getNextPoint(point, m, n, dir);
  }
  return matrix;
}

void printSnakeMatrix(int m, int n) {
  cout << "matrix " << m << " * " << n << ": " << endl;
  vector<vector<int> > v = snakeMatrix(m, n);
  for (int i = 0; i < m; i++) {
    for (int j = 0; j < n; j++) {
      cout << v[i][j] << ", ";
    }
    cout << endl;
  }
}

int main() {
  printSnakeMatrix(3, 3);
  printSnakeMatrix(4, 4);
  printSnakeMatrix(3, 1);
  printSnakeMatrix(3, 4);
  printSnakeMatrix(3, 6);
  printSnakeMatrix(3, 7);
  printSnakeMatrix(4, 1);
  printSnakeMatrix(4, 3);
  printSnakeMatrix(4, 8);
  printSnakeMatrix(4, 9);
  return 0;
}