src/bin/path-sum-ii.rs

Author: bestgopher

src/bin/path-sum-ii.rs

@@ -0,0 +1,73 @@
+fn main() {}
+
+struct Solution;
+
+// 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 {
+    pub fn path_sum(root: Option<Rc<RefCell<TreeNode>>>, target_sum: i32) -> Vec<Vec<i32>> {
+        match Self::f(root, target_sum) {
+            Some(x) => x,
+            None => vec![]
+        }
+    }
+
+    fn f(root: Option<Rc<RefCell<TreeNode>>>, target_sum: i32) -> Option<Vec<Vec<i32>>> {
+        if root.is_none() {
+            return None;
+        }
+
+        let value = root.as_ref().unwrap().borrow().val;
+        let left = root.as_ref().unwrap().borrow_mut().left.take();
+        let right = root.as_ref().unwrap().borrow_mut().right.take();
+
+        if target_sum - value == 0 {
+            if left.is_none() && right.is_none() {
+                return Some(vec![vec![value]]);
+            }
+        }
+
+        let mut left = match Self::f(left, target_sum - value) {
+            Some(mut x) => {
+                x.iter_mut().for_each(|x| x.insert(0, value));
+                x
+            }
+            None => vec![]
+        };
+
+        let mut right = match Self::f(right, target_sum - value) {
+            Some(mut x) => {
+                x.iter_mut().for_each(|x| x.insert(0, value));
+                x
+            }
+            None => vec![]
+        };
+
+        right.append(&mut left);
+        if right.len() == 0 {
+            None
+        } else {
+            Some(right)
+        }
+    }
+}