515. Find Largest Value in Each Tree Row

最新推荐文章于 2025-01-13 15:16:10 发布

原创最新推荐文章于 2025-01-13 15:16:10 发布 · 243 阅读

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本文介绍了一种算法，用于找到二叉树每一层的最大值。通过使用队列实现广度优先搜索，该算法能有效地遍历二叉树的所有层级，并记录下每个层级的最大值。

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

/**
 * 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) {
    	if(root == nullptr)
    	return {};
        vector<int> solution; 
        queue<TreeNode*> q;
        queue<int> level;
        q.push(root);
        level.push(0);
        int l = -1;
        while(q.size())
        {
        	TreeNode* r = q.front();
        	q.pop();
        	int lv = level.front();
        	level.pop();
        	if(r->left)
        	{
        		q.push(r->left);
        		level.push(lv+1);
        	}
        	if(r->right)
        	{
        		q.push(r->right);
        		level.push(lv+1);
        	}
        	if(lv > l)
        	{
        		solution.push_back(r->val);
        		l = lv;
        	}
        	else
        	{
        		if(r->val > solution[lv])
        		solution[lv] = r->val;
        	}
        }
        return solution;
    }
};