. - 力扣(LeetCode)
class Solution {
public:
bool circularArrayLoop(vector<int>& nums) {
int n = nums.size();
auto next = [&](int cur) {
return ((cur + nums[cur]) % n + n) % n; // 保证返回值在 [0,n) 中
};
for (int i = 0; i < n; i++) {
if (!nums[i]) {
continue;
}
int slow = i, fast = next(i);
// 判断非零且方向相同
while (nums[slow] * nums[fast] > 0 && nums[slow] * nums[next(fast)] > 0) {
if (slow == fast) {
if (slow != next(slow)) {
return true;
} else {
break;
}
}
slow = next(slow);
fast = next(next(fast));
}
int add = i;
while (nums[add] * nums[next(add)] > 0) {
int tmp = add;
add = next(add);
nums[tmp] = 0;
}
}
return false;
}
};