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Added cleaner resolution for level-2 n_queens

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This commit is contained in:
Rui Ribeiro 2025-09-29 22:28:33 +01:00
parent 94ff9315d7
commit eb777e722d
1 changed files with 52 additions and 77 deletions
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129
level-2/n_queens/n_queens_clean.c
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@ -1,93 +1,68 @@
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h> #include <stdio.h>
#include <stdlib.h>
void ft_putchar(char c) int *board;
int target;
int ft_abs(int value)
{ {
write(1, &c, 1); if (value < 0)
return (value * -1);
return (value);
} }
void ft_putnbr(int n) void print_board()
{ {
if (n >= 10) int i = 0;
ft_putnbr(n / 10); while (i < target)
ft_putchar((n % 10) + '0'); {
if (i == 0)
fprintf(stdout, "%i", board[i]);
else
fprintf(stdout, " %i", board[i]);
i++;
}
fprintf(stdout,"\n");
} }
void print_solution(int *board, int n) int is_safe(int row, int col)
{ {
int i = 0; int c = 0;
while (i < n) while (c < col)
{ {
ft_putnbr(board[i]); if (board[c] == row)
if (i < n - 1) return (0);
ft_putchar(' '); if (ft_abs(board[c] - row) == ft_abs(col -c))
i++; return (0);
} c++;
ft_putchar('\n'); }
return (1);
} }
int ft_abs(int nbr) void solve(int col)
{ {
if (nbr < 0) if (col == target)
return (nbr * -1); return (print_board());
else
return (nbr); int row = 0;
while (row < target)
{
if (is_safe(row, col))
{
board[col] = row;
solve(col + 1);
}
row++;
}
} }
int is_safe(int *board, int n, int row, int col) int main(int ac, char **av)
{ {
int i; if (ac != 2)
return (1);
i = 0; target = atoi(av[1]);
(void)n; board = (int *)calloc(target, sizeof(int));
while (i < col) solve(0);
{ free(board);
if (board[i] == row) return (0);
return (0);
if (ft_abs(board[i] - row) == (col - i))
return (0);
i++;
}
return (1);
}
void solve(int *board, int n, int col)
{
if (col == n)
return(print_solution(board, n));
int row = 0;
while (row < n)
{
if (is_safe(board, n, row, col))
{
board[col] = row;
solve(board, n, col + 1);
}
row++;
}
}
int main(int argc, char **argv)
{
int *board;
int n;
if (argc != 2)
return (fprintf(stderr, "Usage: %s n\n", argv[0]), 1);
n = atoi(argv[1]);
if (n <= 0)
return (0);
board = (int *)malloc(sizeof(int) * n);
if (!board)
{
fprintf(stderr, "Memory allocation failed\n");
return (1);
}
solve(board, n, 0);
free(board);
return (0);
} }