Solution.cpp

#include<bits/stdc++.h>

using namespace std;

/**
 * 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:
    TreeNode* buildTree(vector<int>& inorder, vector<int>& postorder) {
        if(postorder.empty()){
            return nullptr;
        }
        int left_size = ranges::find(inorder, postorder.back()) - inorder.begin();
        vector<int> in1(inorder.begin(), inorder.begin() + left_size);
        vector<int> in2(inorder.begin() + left_size + 1, inorder.end());
        vector<int> post1(postorder.begin(), postorder.begin() + left_size);
        vector<int> post2(postorder.begin() + left_size, postorder.end() - 1);
        TreeNode* left = buildTree(in1, post1);
        TreeNode* right = buildTree(in2, post2);
        return new TreeNode(postorder.back(), left, right);
    }
};