1

Author: Ainevsia

notes/src/day18/lc106.md

@@ -36,4 +36,45 @@ public:
 };
 ```
 
-## 学习感想
+## 学习感想
+
+```rust
+
+// Definition for a binary tree node.
+#[derive(Debug, PartialEq, Eq)]
+pub struct TreeNode {
+  pub val: i32,
+  pub left: Option<Rc<RefCell<TreeNode>>>,
+  pub right: Option<Rc<RefCell<TreeNode>>>,
+}
+
+impl TreeNode {
+  #[inline]
+  pub fn new(val: i32) -> Self {
+    TreeNode {
+      val,
+      left: None,
+      right: None
+    }
+  }
+}
+use std::rc::Rc;
+use std::cell::RefCell;
+struct Solution {}
+impl Solution {
+    pub fn build_tree(inorder: Vec<i32>, postorder: Vec<i32>) -> Option<Rc<RefCell<TreeNode>>> {
+        Self::build_tree_ref(&inorder, &postorder)
+    }
+
+    pub fn build_tree_ref(inorder: &[i32], postorder: &[i32]) -> Option<Rc<RefCell<TreeNode>>> {
+        if inorder.len() == 0usize { return None }
+        let n: usize = inorder.len();
+        let mut num = postorder[n - 1usize];
+        let pos: usize = inorder.iter().position(|&x| x == num).unwrap();
+        let mut tn: TreeNode = TreeNode::new(num);
+        tn.left = Self::build_tree_ref(&inorder[..pos], &postorder[..pos]);
+        tn.right = Self::build_tree_ref(&inorder[pos + 1usize .. ], &postorder[pos .. n - 1usize]);
+        Some(Rc::new(RefCell::new(tn)))
+    }
+}
+```