免费下载教学设计的网站_广州十大游戏公司_定制营销型网站建设_企业营销策划是做什么的

• 凡是构造二叉树类题目，都要用前序遍历
• 再次强调，完成二叉树的问题，主要就是遍历顺序密切相关，但也不绝对，应该是第一要务

// d17-leetcode-binarytree-constructmaximumbinarytree.cpp
#include <iostream>
#include <vector>
#include <sstream>
#include <climits>struct TreeNode {int val;TreeNode* left;TreeNode* right;TreeNode(): val(0), left(nullptr), right(nullptr) {}TreeNode(int v): val(v), left(nullptr), right(nullptr) {}TreeNode(int v, TreeNode* l, TreeNode* r): val(v), left(l), right(r) {}
};class Solution {
private:TreeNode* traversal(std::vector<int>& nums, int left, int right) {if (left >= right)return nullptr;int maxIndex = left;for (int i = left + 1; i < right; ++i) {if (nums.at(i) > nums.at(maxIndex))maxIndex = i;}TreeNode* node = new TreeNode(nums.at(maxIndex));node->left = traversal(nums, left, maxIndex);node->right = traversal(nums, maxIndex + 1, right);return node;}
public:TreeNode* constructMaximumBinaryTree(std::vector<int>& nums) {return traversal(nums, 0, nums.size());}
};std::vector<int> vec;
void getNums() {std::string str;getline(std::cin, str);std::stringstream ss {str};int v;while(ss >> v)vec.push_back(v);
}
void showTree(TreeNode* node) {if (node == nullptr)return;std::cout << node->val << " ";showTree(node->left);showTree(node->right);
}int main()
{getNums();Solution s;TreeNode* ptn = s.constructMaximumBinaryTree(vec);showTree(ptn);std::cout << std::endl;return 0;
}

• 汇总