1302.deepest-leaves-sum.cpp

/*
 * @lc app=leetcode id=1302 lang=cpp
 *
 * [1302] Deepest Leaves Sum
 *
 * https://leetcode.com/problems/deepest-leaves-sum/description/
 *
 * algorithms
 * Medium (84.03%)
 * Likes:    1133
 * Dislikes: 56
 * Total Accepted:    87.1K
 * Total Submissions: 103K
 * Testcase Example:  '[1,2,3,4,5,null,6,7,null,null,null,null,8]'
 *
 * Given the root of a binary tree, return the sum of values of its deepest
 * leaves.
 * 
 * Example 1:
 * 
 * 
 * Input: root = [1,2,3,4,5,null,6,7,null,null,null,null,8]
 * Output: 15
 * 
 * 
 * Example 2:
 * 
 * 
 * Input: root = [6,7,8,2,7,1,3,9,null,1,4,null,null,null,5]
 * Output: 19
 * 
 * 
 * 
 * Constraints:
 * 
 * 
 * The number of nodes in the tree is in the range [1, 10^4].
 * 1 <= Node.val <= 100
 * 
 * 
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    int deepestLeavesSum(TreeNode* root) {
        if (!root) return 0;
        queue<TreeNode*> que;
        que.push(root);
        int sum = 0;
        while (!que.empty()) {
            int size = que.size();
            if (size != 0)
                sum = 0;
            for (int i = 0; i < size; ++i) {
                TreeNode* node = que.front();
                que.pop();
                sum += node->val;
                if (node->left)
                    que.push(node->left);
                if (node->right)
                    que.push(node->right);
            }
        }
        return sum;
    }
};
// @lc code=end