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]
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就是找出二叉树的每一层的最大数。用BFS较为简单。
C++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> vec; if(!root){ return vec; } queue<TreeNode*> q; q.push(root); while(!q.empty()){ int res = -2147483648; //int类型的最小数。 for(int i = q.size(); i > 0; i--){ auto t = q.front(); q.pop(); if(t->val > res){ res = t->val; } if(t->left) q.push(t->left); if(t->right) q.push(t->right); } vec.push_back(res); } return vec; } };