代码有点渣，效率不够高，简单的层次优先遍历，注意各种情况。。。。比如[],[-12,1,1],[1,-12,0]blablabla题目并没有说不能是负数，注意审题，好好考虑极端情况。
自己的代码
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
vector<int> largestValues(TreeNode* root) {
vector<int> output;
queue<TreeNode *> bfs;
queue<int> depth;
int now = 1, max = 0;
if (root != NULL){
bfs.push(root);
depth.push(1);
max = root -> val;
while (bfs.size()){
if (depth.front() != now){
output.push_back(max);
max = bfs.front() -> val;
now += 1;
}
max = max >= bfs.front() -> val ? max : bfs.front()->val;
if (bfs.front() -> left != NULL){
bfs.push(bfs.front() -> left);
depth.push(now + 1);
}
if (bfs.front() -> right != NULL){
bfs.push(bfs.front() -> right);
depth.push(now + 1);
}
bfs.pop();
depth.pop();
}
output.push_back(max);
}
return output;
}
};
