Change:
// except according to those terms. extern mod extra; <ins> use std::iter::range_step; </ins> use extra::arena::Arena; <ins> use extra::future::Future; </ins> enum Tree<'self> { Nil, <del> Node(&'self Tree<'self>, &'self Tree<'self>, int), </del> <ins> Node(&'self Tree<'self>, &'self Tree<'self>, int) </ins> } fn item_check(t: &Tree) -> int { match *t { <del> Nil => { return 0; } Node(left, right, item) => { return item + item_check(left) - item_check(right); } </del> <ins> Nil => 0, Node(l, r, i) => i + item_check(l) - item_check(r) </ins> } } <del> fn bottom_up_tree<'r>(arena: &'r Arena, item: int, depth: int) -> &'r Tree<'r> { </del> <ins> fn bottom_up_tree<'r>(arena: &'r Arena, item: int, depth: int) -> &'r Tree<'r> { </ins> if depth > 0 { <del> return arena.alloc( || Node(bottom_up_tree(arena, 2 * item - 1, depth - 1), bottom_up_tree(arena, 2 * item, depth - 1), item)); } return arena.alloc(|| Nil); </del> <ins> do arena.alloc { Node(bottom_up_tree(arena, 2 * item - 1, depth - 1), bottom_up_tree(arena, 2 * item, depth - 1), item) } } else {arena.alloc(|| Nil)} </ins> } fn main() { <del> use std::os; use std::int; </del> let args = std::os::args(); <del> let args = if os::getenv("RUST_BENCH").is_some() { ~[~"", ~"17"] </del> <ins> let n = if std::os::getenv("RUST_BENCH").is_some() { 17 </ins> } else if args.len() <= 1u { <del> ~[~"", ~"8"] </del> <ins> 8 </ins> } else { <del> args </del> <ins> from_str(args[1]).unwrap() </ins> }; <del> let n = from_str::<int>(args[1]).unwrap(); </del> let min_depth = 4; <del> let mut max_depth; if min_depth + 2 > n { max_depth = min_depth + 2; } else { max_depth = n; } </del> <ins> let max_depth = if min_depth + 2 > n {min_depth + 2} else {n}; </ins> <del> let stretch_arena = Arena::new(); let stretch_depth = max_depth + 1; let stretch_tree = bottom_up_tree(&stretch_arena, 0, stretch_depth); </del> <ins> { let arena = Arena::new(); let depth = max_depth + 1; let tree = bottom_up_tree(&arena, 0, depth); </ins> <del> println!("stretch tree of depth {}t check: {}", stretch_depth, item_check(stretch_tree)); </del> <ins> println!("stretch tree of depth {}t check: {}", depth, item_check(tree)); } </ins> let long_lived_arena = Arena::new(); let long_lived_tree = bottom_up_tree(&long_lived_arena, 0, max_depth); <del> let mut depth = min_depth; while depth <= max_depth { let iterations = int::pow(2, (max_depth - depth + min_depth) as uint); let mut chk = 0; let mut i = 1; while i <= iterations { let mut temp_tree = bottom_up_tree(&long_lived_arena, i, depth); chk += item_check(temp_tree); temp_tree = bottom_up_tree(&long_lived_arena, -i, depth); chk += item_check(temp_tree); i += 1; } println!("{}t trees of depth {}t check: {}", iterations * 2, depth, chk); depth += 2; </del> <ins> let mut messages = range_step(min_depth, max_depth + 1, 2).map(|depth| { use std::int::pow; let iterations = pow(2, (max_depth - depth + min_depth) as uint); do Future::spawn { let mut chk = 0; for i in range(1, iterations + 1) { let arena = Arena::new(); let a = bottom_up_tree(&arena, i, depth); let b = bottom_up_tree(&arena, -i, depth); chk += item_check(a) + item_check(b); } format!("{}t trees of depth {}t check: {}", iterations * 2, depth, chk) } }).to_owned_vec(); for message in messages.mut_iter() { println(*message.get_ref()); </ins> } println!("long lived tree of depth {}t check: {}", <del> max_depth, item_check(long_lived_tree)); </del> <ins> max_depth, item_check(long_lived_tree)); </ins> }

Discussion:
Several of them do not report the correct results, per Isaac Gouy:
Confirmed that (1) and (5), at least, are still issues. I'm not sure I understand (2), (3), and (4).
The spectralnorm problem was solved in by
This shouldn't be closed; as pointed out at , the last problem (binarytrees) is not yet fixed.
Visiting for triage. This should be dealt with, but it should be considered low priority.