leetcode

0 class Solution {

1 public:

2 bool canReach(const vector<int> &arr, int start) {

3 bitset<50001> bs;

4 queue<int> q({start});

5 while (!q.empty()) {

6 const int idx = q.front();

7 q.pop();

8 const int left = idx - arr[idx], right = idx + arr[idx];

9

10 if (right < arr.size() && !bs[right]) {

11 if (!arr[right]) return true;

12 bs.set(right);

13 q.push(right);

14 }

15

16 if (left >= 0 && !bs[left]) {

17 if (!arr[left]) return true;

18 bs.set(left);

19 q.push(left);

20 }

21 }

22

23 return false;

24 }

25 };