SpiralCounter

main.go

package main

import "fmt"

func main() {
	var rows, columns int
	fmt.Scan(&rows, &columns)

	matrix := make([][]int, rows)
	for c := 0; c < rows; c++ {
		matrix[c] = make([]int, columns)
	}

	var x_min, x_max, x_vector, y_vector, x, y int
	var y_min, y_max int

	x_min, x_max = 0, rows
	y_min, y_max = 0, columns
	x_vector, y_vector = 0, 1
	x, y = 0, 0

	for i := 0; i < rows*columns; i++ {
		matrix[x][y] = i

		x += x_vector
		y += y_vector

		if y == y_max-1 && y_vector == 1 {
			y_vector = 0
			x_vector = 1
			x_min += 1
		}
		if x == x_max-1 && x_vector == 1 {
			x_vector = 0
			y_vector = -1
			y_max -= 1
		}
		if y == y_min && y_vector == -1 {
			y_vector = 0
			x_vector = -1
			x_max -= 1
		}
		if x == x_min && x_vector == -1 {
			y_vector = 1
			x_vector = 0
			y_min -= 1
		}
	}
	PrintMatrix(matrix, rows, columns)
}

func PrintMatrix(matrix [][]int, rows, columns int) {
	for i := 0; i < rows; i++ {
		for j := 0; j < columns; j++ {
			if j == columns-1 {
				fmt.Printf("%4d\n", matrix[i][j])
			} else {
				fmt.Printf("%4d", matrix[i][j])
			}
		}
	}
}
// input 2 3
// prints
//    0   1   2
//    5   4   3

// input 3 3
// prints
//    0   1   2
//    7   8   3
//    6   5   4

// etc.