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Problem 61

Easy

1 · Worked examples

0 / 3

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.

solution()
returns

2 · Which problem is it?

Locked until you have predicted 3 outputs correctly.

The accepted solution

1struct Node {
2 int val;
3 Node* next;
4};
5
6Node* build(const vector<int>& values) {
7
8 Node stub{0, nullptr};
9 Node* tail = &stub;
10
11 for (int v : values) {
12 tail->next = new Node{v, nullptr};
13 tail = tail->next;
14 }
15
16 return stub.next;
17}
18
19vector<int> spill(Node* head) {
20
21 vector<int> out;
22
23 for (Node* p = head; p; p = p->next) {
24 out.push_back(p->val);
25 }
26
27 return out;
28}
29
30Node* weave(Node* a, Node* b) {
31
32 Node stub{0, nullptr};
33 Node* tail = &stub;
34
35 while (a && b) {
36
37 if (a->val <= b->val) {
38 tail->next = a;
39 a = a->next;
40 } else {
41 tail->next = b;
42 b = b->next;
43 }
44
45 tail = tail->next;
46 }
47
48 if (a) {
49 tail->next = a;
50 } else {
51 tail->next = b;
52 }
53
54 return stub.next;
55}
56
57vector<int> solution(const vector<int>& left,
58 const vector<int>& right) {
59
60 Node* a = build(left);
61 Node* b = build(right);
62
63 return spill(weave(a, b));
64}

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.