q662

Author: OhBonsai

src/tree/mod.rs

@@ -137,4 +137,5 @@ mod q108;
 mod q95;
 mod q129;
 mod q1382;
-mod q199;
+mod q199;
+mod q662;

src/tree/q662.rs

@@ -0,0 +1,112 @@
+/// 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:
+///
+/// The given binary tree will have between 1 and 3000 nodes.
+///
+/// 来源：力扣（LeetCode）
+/// 链接：https://leetcode-cn.com/problems/maximum-width-of-binary-tree
+/// 著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。
+
+
+use super::*;
+
+use std::collections::VecDeque;
+use std::cmp::max;
+
+struct Solution{}
+impl Solution {
+    pub fn width_of_binary_tree(root: Option<Rc<RefCell<TreeNode>>>) -> i32 {
+
+        let mut max_width = 0;
+        let mut current_height = 0;
+        let mut left = 0;
+        let mut queue = VecDeque::new();
+        queue.push_front((root, 0, 0));
+
+        while !queue.is_empty() {
+            match queue.pop_back() {
+                Some((Some(n), pos, height) ) => {
+                    queue.push_front((RefCell::borrow(&n).left.clone(), pos * 2, height + 1));
+                    queue.push_front((RefCell::borrow(&n).right.clone(), pos * 2 + 1, height + 1));
+
+                    if current_height != height {
+                        current_height = height;
+                        left = pos
+                    }
+
+                    max_width = max(max_width, pos-left+1);
+                },
+                _ => ()
+            }
+
+        }
+
+        max_width
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1() {
+        assert_eq!(Solution::width_of_binary_tree(tree!(1,2,3)), 2)
+   }
+}
+