tasks a-s

Task/Permutations/Pascal/permutations.pascal

@@ -0,0 +1,71 @@
+program perm;
+
+var
+	p: array[1 .. 12] of integer;
+	is_last: boolean;
+	n: integer;
+
+procedure next;
+var i, j, k, t: integer;
+begin
+is_last := true;
+i := n - 1;
+while i > 0 do
+	begin
+	if p[i] < p[i + 1] then
+		begin
+		is_last := false;
+		break;
+		end;
+	i := i - 1;
+	end;
+
+if not is_last then
+	begin
+	j := i + 1;
+	k := n;
+	while j < k do
+		begin
+		t := p[j];
+		p[j] := p[k];
+		p[k] := t;
+		j := j + 1;
+		k := k - 1;
+		end;
+		
+	j := n;
+	while p[j] > p[i] do j := j - 1;
+	j := j + 1;
+
+	t := p[i];
+	p[i] := p[j];
+	p[j] := t;
+	end;
+end;
+
+procedure print;
+var i: integer;
+begin
+for i := 1 to n do write(p[i], ' ');
+writeln;
+end;
+
+procedure init;
+var i: integer;
+begin
+n := 0;
+while (n < 1) or (n > 10) do
+	begin
+	write('Enter n (1 <= n <= 10): ');
+	readln(n);
+	end;
+for i := 1 to n do p[i] := i;
+end;
+
+begin
+init;
+repeat
+	print;
+	next;
+until is_last;
+end.