Type an input and write what you think is the output . Each problem is converted to Web Assembly, so any possible input will show the corresponding output. Only correct predictions count.
Locked until you have predicted 3 outputs correctly.
| 1 | struct Node { |
| 2 | int val; |
| 3 | Node* left; |
| 4 | Node* right; |
| 5 | }; |
| 6 | |
| 7 | vector<optional<int>> spill(Node* root) { |
| 8 | |
| 9 | vector<optional<int>> out; |
| 10 | |
| 11 | if (!root) { |
| 12 | return out; |
| 13 | } |
| 14 | |
| 15 | queue<Node*> q; |
| 16 | q.push(root); |
| 17 | |
| 18 | while (!q.empty()) { |
| 19 | |
| 20 | Node* node = q.front(); |
| 21 | q.pop(); |
| 22 | |
| 23 | if (!node) { |
| 24 | out.push_back(nullopt); |
| 25 | continue; |
| 26 | } |
| 27 | |
| 28 | out.push_back(node->val); |
| 29 | q.push(node->left); |
| 30 | q.push(node->right); |
| 31 | } |
| 32 | |
| 33 | while (!out.empty() && !out.back()) { |
| 34 | out.pop_back(); |
| 35 | } |
| 36 | |
| 37 | return out; |
| 38 | } |
| 39 | |
| 40 | Node* raise(const vector<int>& pre, int& at, |
| 41 | const vector<int>& in, int lo, int hi) { |
| 42 | |
| 43 | if (lo > hi) { |
| 44 | return nullptr; |
| 45 | } |
| 46 | |
| 47 | int value = pre[at]; |
| 48 | at++; |
| 49 | |
| 50 | int cut = lo; |
| 51 | |
| 52 | while (in[cut] != value) { |
| 53 | cut++; |
| 54 | } |
| 55 | |
| 56 | Node* node = new Node{value, nullptr, nullptr}; |
| 57 | |
| 58 | node->left = raise(pre, at, in, lo, cut - 1); |
| 59 | node->right = raise(pre, at, in, cut + 1, hi); |
| 60 | |
| 61 | return node; |
| 62 | } |
| 63 | |
| 64 | vector<optional<int>> solution(const vector<int>& pre, |
| 65 | const vector<int>& in) { |
| 66 | |
| 67 | int at = 0; |
| 68 | int n = in.size(); |
| 69 | |
| 70 | Node* root = raise(pre, at, in, 0, n - 1); |
| 71 | |
| 72 | return spill(root); |
| 73 | } |
Names have been stripped. The signature is the only clue you get for free. Compiled as C++20 with the standard headers and using namespace std; already in scope.