20240611 Finished

src/problem/mod.rs

@@ -146,3 +146,4 @@ mod p101_symmetric_tree;
 mod p114_flatten_binary_tree_to_linked_list;
 mod p112_path_sum;
 mod p129_sum_root_to_leaf_numbers;
+mod p124_binary_tree_maximum_path_sum;

src/problem/p124_binary_tree_maximum_path_sum.rs

@@ -0,0 +1,75 @@
+/**
+ * [124] Binary Tree Maximum Path Sum
+ */
+pub struct Solution {}
+
+use crate::util::tree::{TreeNode, to_tree};
+
+// submission codes start here
+
+// 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;
+impl Solution {
+    fn max_sum(node: &Rc<RefCell<TreeNode>>, result: &mut i32) -> i32 {
+        if node.borrow().left.is_none() && node.borrow().right.is_none() {
+            *result = (*result).max(node.borrow().val);
+
+            return node.borrow().val;
+        }   
+
+        let left_sum = if let Some(left) = &node.borrow().left {
+            Self::max_sum(left, result)
+        } else {
+            0
+        }.max(0);
+
+        let right_sum = if let Some(right) = &node.borrow().right {
+            Self::max_sum(right, result)
+        } else {
+            0
+        }.max(0);
+
+        *result = (*result).max(node.borrow().val + left_sum + right_sum);
+
+        node.borrow().val + left_sum.max(right_sum)
+    }
+
+    pub fn max_path_sum(root: Option<Rc<RefCell<TreeNode>>>) -> i32 {
+        let mut result = i32::MIN;
+
+        if let Some(root) = root {
+            Self::max_sum(&root, &mut result);
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_124() {
+    }
+}