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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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89
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)
ft_putnbr(n / 10);
ft_putchar((n % 10) + '0');
}
void print_solution(int *board, int n)
{ {
int i = 0; int i = 0;
while (i < n) while (i < target)
{ {
ft_putnbr(board[i]); if (i == 0)
if (i < n - 1) fprintf(stdout, "%i", board[i]);
ft_putchar(' '); else
fprintf(stdout, " %i", board[i]);
i++; i++;
} }
ft_putchar('\n'); fprintf(stdout,"\n");
} }
int ft_abs(int nbr) int is_safe(int row, int col)
{ {
if (nbr < 0) int c = 0;
return (nbr * -1); while (c < col)
else
return (nbr);
}
int is_safe(int *board, int n, int row, int col)
{
int i;
i = 0;
(void)n;
while (i < col)
{ {
if (board[i] == row) if (board[c] == row)
return (0); return (0);
if (ft_abs(board[i] - row) == (col - i)) if (ft_abs(board[c] - row) == ft_abs(col -c))
return (0); return (0);
i++; c++;
} }
return (1); return (1);
} }
void solve(int *board, int n, int col) void solve(int col)
{ {
if (col == n) if (col == target)
return(print_solution(board, n)); return (print_board());
int row = 0; int row = 0;
while (row < n) while (row < target)
{ {
if (is_safe(board, n, row, col)) if (is_safe(row, col))
{ {
board[col] = row; board[col] = row;
solve(board, n, col + 1); solve(col + 1);
} }
row++; row++;
} }
} }
int main(int argc, char **argv) int main(int ac, char **av)
{ {
int *board; if (ac != 2)
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); return (1);
} target = atoi(av[1]);
solve(board, n, 0); board = (int *)calloc(target, sizeof(int));
solve(0);
free(board); free(board);
return (0); return (0);
} }