Given a binary tree, write a function to get the maximum width of the given tree. The maximum width of a tree is the maximum width among all levels.
The width of one level is defined as the length between the end-nodes (the leftmost and right most non-null nodes in the level, where the null nodes between the end-nodes are also counted into the length calculation.
It is guaranteed that the answer will in the range of 32-bit signed integer.
Example 1:
Input:
1
/ \
3 2
/ \ \
5 3 9
Output: 4
Explanation: The maximum width existing in the third level with the length 4 (5,3,null,9).
Example 2:
Input:
1
/
3
/ \
5 3
Output: 2
Explanation: The maximum width existing in the third level with the length 2 (5,3).
Example 3:
Input:
1
/ \
3 2
/
5
Output: 2
Explanation: The maximum width existing in the second level with the length 2 (3,2).
Example 4:
Input:
1
/ \
3 2
/ \
5 9
/ \
6 7
Output: 8
Explanation:The maximum width existing in the fourth level with the length 8 (6,null,null,null,null,null,null,7).
Constraints:
1 and 3000 nodes.struct Solution;
use rustgym_util::*;
use std::collections::HashMap;
trait Preorder {
fn preorder(
&self,
row: usize,
pos: u32,
min: &mut HashMap<usize, u32>,
max: &mut HashMap<usize, u32>,
diff: &mut u32,
);
}
impl Preorder for TreeLink {
fn preorder(
&self,
row: usize,
pos: u32,
min: &mut HashMap<usize, u32>,
max: &mut HashMap<usize, u32>,
diff: &mut u32,
) {
if let Some(node) = self {
min.entry(row).or_insert(pos);
max.entry(row).or_insert(pos);
*min.get_mut(&row).unwrap() = min[&row].min(pos);
*max.get_mut(&row).unwrap() = max[&row].max(pos);
*diff = (*diff).max(max[&row] - min[&row] + 1);
let node = node.borrow();
node.left.preorder(row + 1, pos << 1, min, max, diff);
node.right.preorder(row + 1, (pos << 1) + 1, min, max, diff);
}
}
}
impl Solution {
fn width_of_binary_tree(root: TreeLink) -> i32 {
let mut min: HashMap<usize, u32> = HashMap::new();
let mut max: HashMap<usize, u32> = HashMap::new();
let mut res = 0;
root.preorder(0, 0, &mut min, &mut max, &mut res);
res as i32
}
}
#[test]
fn test() {
let root = tree!(1, tree!(3, tree!(5), tree!(3)), tree!(2, None, tree!(9)));
let res = 4;
assert_eq!(Solution::width_of_binary_tree(root), res);
let root = tree!(1, tree!(3, tree!(5), tree!(3)), None);
let res = 2;
assert_eq!(Solution::width_of_binary_tree(root), res);
let root = tree!(1, tree!(3, tree!(5), None), tree!(2));
let res = 2;
assert_eq!(Solution::width_of_binary_tree(root), res);
let root = tree!(
1,
tree!(3, tree!(5, tree!(6), None), None),
tree!(2, None, tree!(9, None, tree!(7)))
);
let res = 8;
assert_eq!(Solution::width_of_binary_tree(root), res);
}