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use std;
enum tree { nil, node(~tree, ~tree, int), }
fn item_check(t: ~tree) -> int {
alt *t {
nil { ret 0; }
node(left, right, item) {
ret item + item_check(left) - item_check(right);
}
}
}
fn bottom_up_tree(item: int, depth: int) -> ~tree {
if depth > 0 {
ret ~node(bottom_up_tree(2 * item - 1, depth - 1),
bottom_up_tree(2 * item, depth - 1), item);
} else { ret ~nil; }
}
fn main(args: [str]) {
let n = if vec::len(args) == 2u {
option::get(int::from_str(args[1]))
} else {
8
};
let min_depth = 4;
let mut max_depth;
if min_depth + 2 > n {
max_depth = min_depth + 2;
} else { max_depth = n; }
let stretch_depth = max_depth + 1;
let stretch_tree = bottom_up_tree(0, stretch_depth);
io::println(#fmt("stretch tree of depth %d\t check: %d",
stretch_depth,
item_check(stretch_tree)));
let long_lived_tree = bottom_up_tree(0, max_depth);
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(i, depth);
chk += item_check(temp_tree);
temp_tree = bottom_up_tree(-i, depth);
chk += item_check(temp_tree);
i += 1;
}
io::println(#fmt("%d\t trees of depth %d\t check: %d",
iterations * 2, depth,
chk));
depth += 2;
}
io::println(#fmt("long lived trees of depth %d\t check: %d",
max_depth,
item_check(long_lived_tree)));
}
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