package main

import (
	"fmt"
	"os"
)

func main() {
	matrix := [][]int{{2, 6, 1, 6}, {3, 0, 7, 3}, {3, 1, 9, 6}, {1, 3, 0, 3}}
	checkMat(matrix)
	fmt.Printf("Matrix:\n")
	outMat(matrix)
	fmt.Printf("Determinante: %d", getDet(matrix))

}

func checkMat(mat [][]int) {
	for i := 0; i < len(mat); i++ {
		if len(mat) != len(mat[i]) {
			fmt.Printf("Matrix ungueltig")
			os.Exit(1)
		}

	}
}

func getDet(mat [][]int) int {
	if len(mat) > 1 {
		erg := 0
		neg := false
		var ch = make(chan int)
		for i := 0; i < len(mat); i++ {
			go singleDet(mat, neg, i, ch)
			neg = !neg
		}
		for i := 0; i < len(mat); i++ {
			zw := <-ch
			erg = erg + zw
		}
		return erg
	} else {
		return mat[0][0]
	}

}

func singleDet(mat [][]int, neg bool, i int, ch chan int) {
	erg := 0
	mat1 := [][]int{}
	for j := 0; j < len(mat); j++ {
		if j == i {
			continue
		}
		mat1 = append(mat1, []int{})
		for k := 1; k < len(mat[j]); k++ {
			if j < i {
				mat1[j] = append(mat1[j], mat[j][k])
			} else {
				mat1[j-1] = append(mat1[j-1], mat[j][k])
			}
		}

	}
	if !neg {
		erg = erg + mat[i][0]*getDet(mat1)
	} else {
		erg = erg - mat[i][0]*getDet(mat1)
	}
	ch <- erg
}

func outMat(mat [][]int) {
	for i := 0; i < len(mat); i++ {
		for j := 0; j < len(mat[0]); j++ {
			fmt.Printf("%d ", mat[i][j])
		}
		fmt.Printf("\n")
	}
}