diff --git a/Problem1.py b/Problem1.py
new file mode 100644
index 0000000..b73ee5f
--- /dev/null
+++ b/Problem1.py
@@ -0,0 +1,27 @@
+"""
+Time Complexity: O(n)
+Space Complexity: O(1)
+"""
+# The knows API is already defined for you.
+# return a bool, whether a knows b
+# def knows(a: int, b: int) -> bool:
+
+class Solution:
+    def findCelebrity(self, n: int) -> int:
+        ptnlCand = 0
+
+        for i in range(1, n):
+            if knows(ptnlCand, i):
+                ptnlCand = i
+
+        for i in range(n):
+            if i == ptnlCand:
+                continue
+            if i < ptnlCand:
+                if knows(ptnlCand, i) or not knows(i, ptnlCand):
+                    return -1
+            else:
+                if not knows(i, ptnlCand):
+                    return -1
+
+        return ptnlCand 
\ No newline at end of file