I was studying the 8 queens puzzle and i wrote down my version of code that solved the problem with the first queen always put on row 0.
#include "stdafx.h"
#include <iostream>
using namespace std;
const int NUMBER_OF_QUEENS = 8; // Constant: eight queens
int queens[NUMBER_OF_QUEENS];
// Check whether a queen can be placed at row i and column j
bool isValid(int row, int column)
{
for (int i = 1; i <= row; i++)
if (queens[row - i] == column // Check column
|| queens[row - i] == column - i // Check upper left diagonal
|| queens[row - i] == column + i) // Check upper right diagonal
return false; // There is a conflict
return true; // No conflict
}
// Display the chessboard with eight queens
void printResult()
{
cout << "\n---------------------------------\n";
for (int row = 0; row < NUMBER_OF_QUEENS; row++)
{
for (int column = 0; column < NUMBER_OF_QUEENS; column++)
printf(column == queens[row] ? "| Q " : "| ");
cout << "|\n---------------------------------\n";
}
}
// Search to place a queen at the specified row
bool search(int row)
{
if (row == NUMBER_OF_QUEENS) // Stopping condition
return true; // A solution found to place 8 queens in 8 rows
for (int column = 0; column < NUMBER_OF_QUEENS; column++)
{
queens[row] = column; // Place a queen at (row, column)
if (isValid(row, column) && search(row + 1))
return true; // Found, thus return true to exit for loop
}
// No solution for a queen placed at any column of this row
return false;
}
int main()
{
search(0); // Start search from row 0. Note row indices are 0 to 7
printResult(); // Display result
return 0;
}
Now i want to modify it so it will take user input so it can start from rows 0-7. I’ve put something like this in the main function
int row, col = 0; cout << "Enter a row number from 0-7 "; cin >> row; search(row);// Start search from row 0. Note row indices are 0 to 7 bool yas = isValid(row, col); cout << yas; printResult(); // Display result return 0;
However when I run it, I keep getting a syntax error or false no matter what. Is there a better way to take user input in this or did I logically do this wrong?