Online C++ Compiler

#include <bits/stdc++.h> using namespace std; void print_vector(vector<vector<auto> > v){ cout << "["; for(int i = 0; i<v.size(); i++){ cout << "["; for(int j = 0; j <v[i].size(); j++){ cout << v[i][j] << ", "; } cout << "],"; } cout << "]"<<endl; } struct Node { bool isEnd; map<char, Node *> child; }; class Solution { public: vector<vector<string>> ret; void insertNode(Node *head, string &s) { Node *node = head; for (int i = 0; i < s.size(); i++) { char x = s[i]; if (!node->child[x]) { node->child[x] = new Node(); } node = node->child[x]; } node->isEnd = true; } void getAllWords(int idx, string prefix, Node *node, vector<string> &temp, string curr = "") { if (!node) return; if (node->isEnd) { temp.push_back(curr); return; } if (idx >= prefix.size()) { for (auto &it : node->child) { getAllWords(idx, prefix, it.second, temp, curr + it.first); } } else { char x = prefix[idx]; if (!node->child[x]) return; getAllWords(idx + 1, prefix, node->child[x], temp, curr + x); } } void solve(vector<string> &temp, int idx, int reqSize, Node *head) { if (idx == reqSize) { ret.push_back(temp); return; } string prefix = ""; for (int i = 0; i < temp.size(); i++) { prefix += temp[i][idx]; } vector<string> possible; Node *curr = head; getAllWords(0, prefix, curr, possible); for (int i = 0; i < possible.size(); i++) { string s = possible[i]; temp.push_back(s); solve(temp, idx + 1, reqSize, head); temp.pop_back(); } } vector<vector<string>> wordSquares(vector<string> &words) { ret.clear(); Node *head = new Node(); for (int i = 0; i < words.size(); i++) { insertNode(head, words[i]); } vector<string> temp; for (int i = 0; i < words.size(); i++) { string s = words[i]; temp.push_back(s); solve(temp, 1, (int)words[0].size(), head); temp.pop_back(); } return ret; } }; main() { Solution ob; vector<string> v = {"area", "lead", "wall", "lady", "ball"}; print_vector(ob.wordSquares(v)); }