let tri_tas ineq t =

	let echanger i j =
		let k = t.(i) in
		t.(i) <- t.(j);
		t.(j) <- k;
	in

	let rec entasser n i =
		let g = 2*i+1 and d = 2*i+2 in
		let max = if g < n && ineq t.(i) t.(g) then g else i in
		let max = if d < n && ineq t.(max) t.(d) then d else max in
		if max <> i then (
			echanger i max;
			entasser n max;
		);
	in

	let n = vect_length t in

	for i = n /2 -1 downto 0 do
		entasser n i;
	done;

	for i = n-1 downto 1 do
		echanger i 0;
		entasser i 0;
	done;
;;

let tri_c = tri_tas (prefix <) ;;
let tri_d = tri_tas (prefix >) ;;