broadcast.cpp

#include <omp.h>

#include <iostream>
#include <stdexcept>
#include <vector>

// Function to broadcast two matrices
void broadcast(const std::vector<std::vector<int>>& A,
               std::vector<std::vector<int>>& B) {
  size_t rowsA = A.size();
  size_t colsA = A[0].size();
  size_t rowsB = B.size();
  size_t colsB = B[0].size();

  if (rowsA == 0 || colsA == 0 || rowsB == 0 || colsB == 0) {
    throw std::invalid_argument("Empty matrix cannot be broadcasted");
  }
  if (rowsA != rowsB && rowsB != 1) {
    throw std::invalid_argument("Incompatible dimensions for broadcasting");
  }
  if (colsA != colsB && colsB != 1) {
    throw std::invalid_argument("Incompatible dimensions for broadcasting");
  }

  if (rowsB == 1) {
    B.resize(rowsA, B[0]);
  }
  if (colsB == 1) {
    for (auto& row : B) {
      row.resize(colsA, row[0]);
    }
  }

#pragma omp parallel for
  for (size_t i = 0; i < rowsA; i++) {
#pragma omp parallel for
    for (size_t j = 0; j < colsA; j++) {
      B[i][j] = A[i][j] + B[i][j];
    }
  }
}

int main() {
  std::vector<std::vector<int>> A = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
  std::vector<std::vector<int>> B = {{1, 2, 3}};  // B has only one row

  try {
    broadcast(A, B);
    for (const auto& row : B) {
      for (const auto& elem : row) {
        std::cout << elem << " ";
      }
      std::cout << std::endl;
    }
  } catch (const std::invalid_argument& e) {
    std::cerr << "Error: " << e.what() << std::endl;
  }

  return 0;
}