Add solution for Circular Array Loop

camp1/week3/leetcode/circular-array-loop.py

@@ -0,0 +1,24 @@
+class Solution:
+    def circularArrayLoop(self, nums: List[int]) -> bool:
+
+        visited=defaultdict(int)
+        def nex(i):
+            return (i+nums[i])%len(nums)
+
+        for i in range(len(nums)):
+            if visited[i]==1:
+                continue
+            slow,fast=i,nex(i)
+            while nums[slow]*nums[fast]>0 and nums[slow]*nums[nex(fast)]>0:
+                visited[slow]=1
+                if slow==fast:
+                    if slow!=nex(slow):
+                        return True
+                    break
+                slow=nex(slow)
+                fast=nex(nex(fast))
+        return False
+
+
+
+