문제
Start with n. If it is even, divide it by 2; if it is odd, multiply it by 3 and add 1. Repeat until the value is 1. Include both the starting value and the final 1 in your answer.
Implement collatz_sequence(n).
Input
n: The positive starting integer.
Output
Return the complete sequence in order.
제약 조건
1 ≤ n ≤ 10,000. Inputs in this range reach 1 under this rule; all sequence values fit a signed 64-bit integer.
예시
입력:
n = 6
예상 출력:
expected = [6, 3, 10, 5, 16, 8, 4, 2, 1]입력:
long long n = 6;
예상 출력:
std::vector<long long> expected = {6, 3, 10, 5, 16, 8, 4, 2, 1};입력:
long n = 6;
예상 출력:
long[] expected = new long[] {6, 3, 10, 5, 16, 8, 4, 2, 1};설명
6 is even, so it becomes 3. Then 3 becomes 10. Continue applying the rule until 1.
입력:
n = 1
예상 출력:
expected = [1]입력:
long long n = 1;
예상 출력:
std::vector<long long> expected = {1};입력:
long n = 1;
예상 출력:
long[] expected = new long[] {1};설명
The starting value is already 1, so no transformations are needed.
접근 방법
먼저 스스로 풀어 본 뒤 힌트를 하나씩 열어 보세요.
힌트 1
The sequence is generated by repeatedly applying one rule based on whether the current number is even or odd.
힌트 2
Keep appending each new value until you reach 1.
힌트 3
Watch out that the starting value itself and the final 1 must both appear in the result.
예상 복잡도
O(k) time, O(k) extra space, where k is the sequence length
참고 자료
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