leetcode -- 515. Find Largest Value in Each Tree Row

You need to find the largest value in each row of a binary tree.

Example:
Input:

1
/ \
3 2
/ \ \
5 3 9

Output: [1, 3, 9]

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/find-largest-value-in-each-tree-row
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

我的思路：

1. 用广搜，但是这道题在leetcode上是深搜，我感觉用广搜好解一点，于是选择广搜

2. 因为要记录每一层值，所以在每次进入while循环，先看里面有几个元素，就是每一层的结点个数

3. 然后再在每层中找最大值即可

/*** 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:queue<TreeNode*> q; //存放值vector<int> maxValue;vector<int> largestValues(TreeNode* root) {if(root==NULL) return maxValue;q.push(root);while(!q.empty()){int size = q.size();int maxnV = INT_MIN;for(int i = 0; i < size; i++){TreeNode* front = q.front();int v = front->val; //队头的值maxnV = max(maxnV, v);q.pop();if(front->left) q.push(front->left);if(front->right) q.push(front->right);}maxValue.push_back(maxnV);                 }return maxValue;}
};

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