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Problem 127

Medium

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* drop(Node* head, int n) {
31
32 Node stub{0, head};
33 Node* lead = &stub;
34 Node* trail = &stub;
35
36 for (int i = 0; i < n; i++) {
37 lead = lead->next;
38 }
39
40 while (lead->next) {
41 lead = lead->next;
42 trail = trail->next;
43 }
44
45 trail->next = trail->next->next;
46
47 return stub.next;
48}
49
50vector<int> solution(const vector<int>& values, int n) {
51
52 Node* head = build(values);
53
54 return spill(drop(head, n));
55}

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.