1161. Maximum Level Sum of a Binary Tree 題目： 求一棵樹擁有最大和的層 思路： BFS 進階題 基本上還是跑 BFS 但要記錄最大和並每層更新 如果比較大就更新最大層數 層數也要每輪加一 就是個稍微多一些東西要處理的 BFS Code: use std::cell::RefCell; use std::collections::VecDeque; use std::rc::Rc; impl Solution { pub fn max_level_sum(root: Option<Rc<RefCell<TreeNode>>>) -> i32 { let mut max_level_sum = i32::MIN; let mut curr_level = 1; let mut max_level = 1; let mut queue = VecDeque::new(); if let Some(node) = root { queue.push_back(node); } while !queue.is_empty() { let level_len = queue.len(); let mut local_level_sum = 0; for _ in 0..level_len { if let Some(node) = queue.pop_front() { let mut n_borrow = node.borrow_mut(); local_level_sum += n_borrow.val; if let Some(left) = n_borrow.left.take() { queue.push_back(left); } if let Some(right) = n_borrow.right.take() { queue.push_back(right); } } } if local_level_sum > max_level_sum { max_level_sum = local_level_sum; max_level = curr_level; } curr_level += 1; } max_level } } -- ※ 發信站: 批踢踢實業坊(ptt.org.tw), 來自: 60.248.143.172 (臺灣) ※ 文章網址: https://ptt.org.tw/Marginalman/M.1751451825.A.2F1