1302. 层数最深叶子节点的和
解题思路
- 改造二叉树的层序遍历算法 累计最后一层的和
- 和计算二叉树的每一层的和类似
/**
* 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 {
public int deepestLeavesSum(TreeNode root) {
// 改造二叉树的层序遍历算法 累加最后一层的和
List<List<Integer>> result = new ArrayList<>();
if(root == null){
return 0;
}
Queue<TreeNode> q = new LinkedList<>();// 使用双向链表可以模拟栈结构
q.offer(root);
int sum = 0;
while(!q.isEmpty()){
// 计算此时队列的大小
int size = q.size();
sum = 0;
for(int i = 0; i < size; i++){
// 取出当前队列头部节点
TreeNode cur = q.poll();
sum += cur.val;
if(cur.left != null){
q.offer(cur.left);
}
if(cur.right != null){
q.offer(cur.right);
}
}
}
return sum;
}
}