#include <stdio.h>
#include <stdbool.h>

double matA[4][4] = {
    {1.1161, 0.1254, 0.1397, 0.1490},
    {0.1582, 1.1675, 0.1768, 0.1871},
    {0.2368, 0.2471, 0.2568, 1.2671},
    {0.1968, 0.2071, 1.2168 ,0.2271}
};

double matB[4] = {
    1.5471, 1.6471, 1.8471, 1.7571
};

void rowManipulation(int originRow, double coefficent, int rowBeingAdded) {
    int col = 0;
    for (col = 0; col < 4; col++) {
        matA[rowBeingAdded][col] += matA[originRow][col] * coefficent;
    }
    matB[rowBeingAdded] += matB[originRow] * coefficent;
}

void timesOfRow(int rowCount, double time) {
    int col = 0;
    for (col = 0; col < 4; col++) {
        matA[rowCount][col] *= time;
    }
    matB[rowCount] *= time;
}

int findNoneZeroItem(int startRowIndex, int columnIndex) {
    bool found = false;
    int pos = startRowIndex;
    for (pos = startRowIndex; pos < 4; pos++) {
        if (matA[pos][columnIndex] != 0) {
            return pos;
        }
    }
    return -1;
}

void swapRow(int firstRowIndex, int secondRowIndex) {
    double temp = 0;
    int i = 0;
    for (i = 0; i < 4; i++) {
        temp = matA[firstRowIndex][i];
        matA[firstRowIndex][i] = matA[secondRowIndex][i];
        matA[secondRowIndex][i] = temp;
    }
    temp = matB[firstRowIndex];
    matB[firstRowIndex] = matB[secondRowIndex];
    matB[secondRowIndex] = temp;
}

void printOut() {
    int i = 0, j = 0;
    for (i = 0; i < 4; i++) {
        for (j = 0; j < 4; j++) {
            printf("%lf\t", matA[i][j]);
        }
        printf("%lf", matB[i]);
        printf("\n");
    }
}

int main() {
    int x[4] = {0};
    int column = 0, row = 0;
    int tempRow = 0;
    int noneZeroRow = 0;
    for (column = 0; column < 4; column++) {
        noneZeroRow = findNoneZeroItem(row, column);
        if (noneZeroRow == -1) {
            continue;
        }
        else {
            swapRow(row, noneZeroRow);
            timesOfRow(row, 1.0/matA[row][column]);
            for (tempRow = 0; tempRow < 4; tempRow++) {
                if (tempRow != row)
                rowManipulation(row, -matA[tempRow][column], tempRow);
            }
            row++;
        }
        
    }
    for (row = 0; row < 4; row++) {
        printf("x(%d) = %lf\n", row+1, matB[row]);
    }
    return 0;
}