leetcode

0 class Solution {

1 public:

2 bool circularArrayLoop(vector<int> &nums) const {

3 const int n = size(nums);

4 static int seen[5001];

5

6 const auto next = [&](int k) {

7 const int res = (k + nums[k] % n + n) % n;

8 seen[res] = true;

9 return res;

10 };

11

12 memset(seen, 0x00, sizeof(seen));

13 for (auto &num : nums)

14 num %= n;

15

16 for (int i = 0; i < n; i++) {

17 if (seen[i]) continue;

18 int t = i, h = i;

19

20 do {

21 t = next(t);

22 h = next(next(h));

23 } while (t != h);

24

25 const bool dir = nums[t] > 0;

26 do {

27 t = next(t);

28 if ((nums[t] > 0) != dir) goto next;

29 } while (t != h);

30

31 if ((t + nums[t] + n) % n != t) return true;

32 next:;

33 }

34

35 return false;

36 }

37 };