import numpy as np
import sys
import pprint

def gaus_elimination(A):

    row, col = len(A), len(A[0])

    m = n = 0

    for i in range(row-1):

        while n < col-1 and A[n][i]==0:
            n+=1

        if n == col-1 and A[n][i]==0:
            print("Khong co dang bac thang!! Do cac so hang cua cot"+str(i)+"deu bang 0!");
            sys.exit()

        while m != row:

            if A[m][m]==0:
                A[m-1], A[m] = A[m], A[m-1]
            m+=1

        for j in range(i+1,row):
            temp = A[j][i]/A[i][i]

            for k in range(row):
                A[j][k]=A[j][k]-temp*A[i][k]

    return A

A=[[1,2,3,-2],
    [-2,1,2,3],
    [3,2,-1,2],
    [2,-3,2,1]]
B=[6,-8,4,-8]

result=np.linalg.solve(A, B)
print("Nghiem cua he phuong trinh tuyen tinh la:");
print(result);
print("\n");
    
M = [[2,-1,0,5],
    [-4,-1,4,-12],
    [-2,-5,7,-6],
    [6,0,-3,20]]

M = gaus_elimination(M)
print("Ma tran duoc bien doi bang phuong phap Gauss:");
pprint.pprint(M)