Bfs

1302. Deepest Leaves Sum Given the root of a binary tree, return the sum of values of its deepest leaves. Example 1: Input: root = [1,2,3,4,5,null,6,7,null,null,null,null,8] Output: 15 Example 2: Input: root = [6,7,8,2,7,1,3,9,null,1,4,null,null,null,5] Output: 19 Constraints: The number of nodes in the tree is in the range [1, 104]. 1 <= Node.val <= 100 Solution /** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode() {} * TreeNode(int val) { this.val = val; } * TreeNode(int val, TreeNode left, TreeNode right) { * this.val = val; * this.left = left; * this.right = right; * } * } */ class Solution { TreeNode[] q = new TreeNode[10_000]; int head; int tail; public int deepestLeavesSum(TreeNode root) { if (root == null) return 0; q[tail++] = root; int sum = 0; while (head != tail) { TreeNode node = q[head]; sum = 0; int size = tail - head; for (int i = 0; i < size; i++) { node = q[head++]; sum += node.val; if (node.left != null) q[tail++] = node.left; if (node.right != null) q[tail++] = node.right; } } return sum; } }

![https://leetcode.com/problems/sliding-puzzle/] On a 2x3 board, there are 5 tiles represented by the integers 1 through 5, and an empty square represented by 0. A move consists of choosing 0 and a 4-directionally adjacent number and swapping it. The state of the board is solved if and only if the board is [[1,2,3],[4,5,0]]. Given a puzzle board, return the least number of moves required so that the state of the board is solved. If it is impossible for the state of the board to be solved, return -1. ...