This code solves the N-Queens problem for a given value...

April 23, 2024 at 05:37 AM

#include <stdio.h>
#define MAX 10

int is_attack(int row, int col, int n, int board[][MAX]) {
    int i, j;
    for (i = 0; i < row; i++) {
        if (board[i][col])
            return 1;
        for (j = 0; j < n; j++) {
            if (board[i][j] && (i-j == row-col || i+j == row+col))
                return 1;
        }
    }
    return 0;
}

int n_queens(int row, int n, int board[][MAX]) {
    int i, res = 0;
    if (row == n)
        return 1;
    for (i = 0; i < n; i++) {
        board[row][i] = 1;
        if (!is_attack(row, i, n, board)) {
            res += n_queens(row+1, n, board);
        }
        board[row][i] = 0;
    }
    return res;
}

int main() {
    int n, i, j, board[MAX][MAX] = {0};
    printf("Enter the value of n: ");
    scanf("%d", &n);
    int res = n_queens(0, n, board);
    if (res == 0)
        printf("There is no solution for this problem\n");
    else
        printf("There are %d solutions for this problem\n", res);
    return 0;
}

This code solves the N-Queens problem for a given value of n, where n represents the size of the chessboard (n x n). The program finds and prints the number of possible solutions to place n queens on an n x n chessboard such that no two queens attack each other.

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