path_sum.rs

use std::rc::Rc;
use std::cell::RefCell;
impl Solution {
    pub fn has_path_sum(root: Option<Rc<RefCell<TreeNode>>>, target_sum: i32) -> bool {
        if let Some(curr_node) = root {
            let curr_node = curr_node.borrow();
            if curr_node.left.is_none() && curr_node.right.is_none() && curr_node.val == target_sum {
                return true
            }
            return Self::has_path_sum(curr_node.left.clone(), target_sum - curr_node.val) ||
                   Self::has_path_sum(curr_node.right.clone(), target_sum - curr_node.val)
        }
        return false
    }
}