#include <stdio.h>
#include <stdlib.h>

int createMatrix(int rows, int columns, int **matrix);
int displayMatrix(int rows, int columns, int **matrix);
int matrixAddition(int rows, int columns);
int matrixSubtraction(int rows, int columns);
int matrixTranspose(int rows, int columns);
int matrixMultiplication(int rowsA, int rowsB, int columnsA, int columnsB);

int main() {
  while (1) {
    int opt;
    printf("\n1. Create and display a matrix\n");
    printf("2. Matrix Addition\n");
    printf("3. Matrix Subtraction\n");
    printf("4. Matrix Transpose\n");
    printf("5. Matrix Multiplication\n");
    printf("6. Quit the program.\n");

    printf("\nEnter your selection: ");
    scanf("%d", &opt);

    if (opt == 1) {
      printf("\nYou chose to create a matrix and display it\n");
      int rows, columns;
      printf("Enter the number of rows: ");
      scanf("%d", &rows);

      printf("Enter the number of columns: ");
      scanf("%d", &columns);

      int **matrix = malloc(rows * sizeof(int*));

      for (int i=0; i<rows; i++) {
        matrix[i] = malloc(columns * sizeof(int*));
      }

      createMatrix(rows, columns, matrix);
      printf("\nResultant Matrix: \n");
      displayMatrix(rows, columns, matrix);

      for (int i=0; i<rows; i++) {
        free(matrix[i]);
      }

      free(matrix);
    }

    else if (opt == 2) {
      printf("\nYou chose Matrix Addition\n");
      int rows, columns;

      printf("Enter the number of rows: ");
      scanf("%d", &rows);

      printf("Enter the number of columns: ");
      scanf("%d", &columns);

      matrixAddition(rows, columns);
    }

    else if(opt == 3){
      printf("\nYou chose Matrix Subtraction\n");
      int rows, columns;

      printf("Enter the number of rows: ");
      scanf("%d", &rows);

      printf("Enter the number of columns: ");
      scanf("%d", &columns);

      matrixSubtraction(rows, columns);
    }

    else if(opt == 4){
      printf("\nYou chose Matrix Transpose\n");

      int rows, columns;

      printf("Enter the number of rows: ");
      scanf("%d", &rows);

      printf("Enter the number of columns: ");
      scanf("%d", &columns);

      matrixTranspose(rows, columns);
    }

    else if(opt == 5){
      printf("\nYou chose Matrix Multiplication\n");
      int rowsA, rowsB, columnsA, columnsB;

      printf("Enter the number of rows of the first matrix: ");
      scanf("%d", &rowsA);

      printf("Enter the number of columns of the first matrix: ");
      scanf("%d", &columnsA);

      printf("Enter the number of rows of the second matrix: ");
      scanf("%d", &rowsB);

      printf("Enter the number of columns of the second matrix: ");
      scanf("%d", &columnsB);

      matrixMultiplication(rowsA, rowsB, columnsA, columnsB);
    }

    else if(opt == 6) {
      printf("\nYou chose to quit the program\n");
      return 0;
    }

    else {
      printf("\nInvalid option, try again\n");
    }
  }
}

int createMatrix(int rows, int columns, int **matrix) {
  for (int i=0; i<rows; i++) {
    for (int j=0; j<columns; j++) {
      printf("Enter the \"%d*%d\"th element: ", i+1, j+1);
      scanf("%d", &matrix[i][j]);
    }
  }
  return 0;
}

int matrixAddition(int rows, int columns) {
  printf("\nMatrix A: \n");
  int **matrixA = malloc(rows * sizeof(int*));
  for (int i=0; i<rows; i++) {
    matrixA[i] = malloc(columns * sizeof(int*));
  }
  createMatrix(rows, columns, matrixA);

  printf("\nMatrix B: \n");
  int **matrixB = malloc(rows * sizeof(int*));
  for (int i=0; i<rows; i++) {
    matrixB[i] = malloc(columns * sizeof(int*));
  }
  createMatrix(rows, columns, matrixB);

  int **matrixC = malloc(rows * sizeof(int*));
  for (int i=0; i<rows; i++) {
    matrixC[i] = malloc(columns * sizeof(int*));
  }

  for (int i=0; i<rows; i++) {
    for (int j=0; j<columns; j++) {
      matrixC[i][j] = matrixA[i][j] + matrixB[i][j];
    }
  }

  printf("\nResultant Matrix: \n");
  displayMatrix(rows, columns, matrixC);

  for (int i=0; i<rows; i++) {
    free(matrixA[i]);
  }
  free(matrixA);

  for (int i=0; i<rows; i++) {
    free(matrixB[i]);
  }
  free(matrixB);

  for (int i=0; i<rows; i++) {
    free(matrixC[i]);
  }
  free(matrixC);

  return 0;

}

int matrixSubtraction(int rows, int columns) {
  printf("\nMatrix A: \n");
  int **matrixA = malloc(rows * sizeof(int*));
  for (int i=0; i<rows; i++) {
    matrixA[i] = malloc(columns * sizeof(int*));
  }
  createMatrix(rows, columns, matrixA);

  printf("\nMatrix B: \n");
  int **matrixB = malloc(rows * sizeof(int*));
  for (int i=0; i<rows; i++) {
    matrixB[i] = malloc(columns * sizeof(int*));
  }
  createMatrix(rows, columns, matrixB);

  int **matrixC = malloc(rows * sizeof(int*));
  for (int i=0; i<rows; i++) {
    matrixC[i] = malloc(columns * sizeof(int*));
  }

  for (int i=0; i<rows; i++) {
    for (int j=0; j<columns; j++) {
      matrixC[i][j] = matrixA[i][j] - matrixB[i][j];
    }
  }

  printf("\nResultant Matrix: \n");
  displayMatrix(rows, columns, matrixC);

  for (int i=0; i<rows; i++) {
    free(matrixA[i]);
  }
  free(matrixA);

  for (int i=0; i<rows; i++) {
    free(matrixB[i]);
  }
  free(matrixB);

  for (int i=0; i<rows; i++) {
    free(matrixC[i]);
  }
  free(matrixC);

  return 0;
}

int displayMatrix(int rows, int columns, int **matrix) {
  for (int i=0; i<rows; i++) {
    for (int j=0; j<columns; j++) {
      printf("%d\t", matrix[i][j]);
    }
    printf("\n");
  }
  return 0;
}

int matrixTranspose(int rows, int columns) {
  int **matrixA = malloc(rows * sizeof(int*));
  for (int i=0; i<rows; i++) {
    matrixA[i] = malloc(columns * sizeof(int*));
  }
  printf("\nMatrix A: \n");
  createMatrix(rows, columns, matrixA);

  int **matrixB = malloc(columns * sizeof(int*));
  for (int i=0; i<columns; i++) {
    matrixB[i] = malloc(rows * sizeof(int*));
  }

  for (int i=0; i<rows; i++) {
    for (int j=0; j<columns; j++) {
      matrixB[j][i] = matrixA[i][j];
    }
  }

  printf("\nResultant Matrix: \n");
  displayMatrix(columns, rows, matrixB);

  for (int i=0; i<rows; i++) {
    free(matrixA[i]);
  }
  free(matrixA);

  for (int i=0; i<columns; i++) {
    free(matrixB[i]);
  }
  free(matrixB);

  return 0;
}

int matrixMultiplication(int rowsA, int rowsB, int columnsA, int columnsB) {
  if (rowsB != columnsA) {
    printf("Number of columns of the first matrix should be equal to number of rows of the second matrix.\n");
    return 0;
  }

  int **matrixA = malloc(rowsA * sizeof(int*));
  for (int i=0; i<rowsA; i++) {
    matrixA[i] = malloc(columnsA * sizeof(int*));
  }

  int **matrixB = malloc(rowsB * sizeof(int*));
  for (int i=0; i<rowsB; i++) {
    matrixB[i] = malloc(columnsB * sizeof(int*));
  }

  int **matrixC = malloc(rowsA * sizeof(int*));
  for (int i=0; i<rowsA; i++) {
    matrixC[i] = malloc(columnsB * sizeof(int*));
  }

  printf("\nMatrix A: \n");
  createMatrix(rowsA, columnsA, matrixA);

  printf("\nMatrix B: \n");
  createMatrix(rowsB, columnsB, matrixB);

  for (int i=0; i<rowsA; i++) {
    for (int j=0; j<columnsB; j++) {
      matrixC[i][j] = 0;
      for (int k=0; k<columnsA; k++) {
        matrixC[i][j] += matrixA[i][k] * matrixB[k][j];
      }
    }
  }

  displayMatrix(rowsA, columnsB, matrixC);

  for (int i=0; i<rowsA; i++) {
    free(matrixA[i]);
  }
  free(matrixA);

  for (int i=0; i<rowsB; i++) {
    free(matrixB[i]);
  }
  free(matrixB);

  for (int i=0; i<rowsA; i++) {
    free(matrixC[i]);
  }
  free(matrixC);

  return 0;
}