Deepest Leaves Sum

给一个二叉树, 返回最后一层的sum. 这个题我用的是层序扫描.

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    int res = 0;
    public int deepestLeavesSum(TreeNode root) {
        if(root == null)
            return res;
        Queue<TreeNode> q = new LinkedList<>();
        q.add(root);
        List<TreeNode> list = new ArrayList<>();
        while(q.size() != 0) {
            int size = q.size();
            List<TreeNode> tmp = new ArrayList<>();
            for(int i = 0; i < size; i++) {
                TreeNode n = q.poll();
                tmp.add(n);
                if(n.left != null)
                    q.add(n.left);
                if(n.right != null)
                    q.add(n.right);
            }
            list = tmp;
        }
        
        for(TreeNode node : list)
            res += node.val;
        return res;
    }
}

/**

* Definition for a binary tree node.

* public class TreeNode {

* int val;

* TreeNode left;

* TreeNode right;

* TreeNode(int x) { val = x; }

* }

class Solution {

int res = 0;

public int deepestLeavesSum(TreeNode root) {

if(root == null)

return res;

Queue<TreeNode> q = new LinkedList<>();

q.add(root);

List<TreeNode> list = new ArrayList<>();

while(q.size() != 0) {

int size = q.size();

List<TreeNode> tmp = new ArrayList<>();

for(int i = 0; i < size; i++) {

TreeNode n = q.poll();

tmp.add(n);

if(n.left != null)

q.add(n.left);

if(n.right != null)

q.add(n.right);

}

list = tmp;

}

for(TreeNode node : list)

res += node.val;

return res;

}

Deepest Leaves Sum

书脊

这青苔碧瓦堆, 俺曾睡风流觉, 将五十年兴亡看饱.

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