Missing Number Solution

Author: doh6077

missing-number/doh6077.py

@@ -0,0 +1,16 @@
+# Missing Number
+class Solution:
+    def missingNumber(self, nums: List[int]) -> int:
+        # First Solution: Time Complexity: O(n^2)
+        n = len(nums)
+
+        for i in range(0,n + 1):
+            if i not in nums:
+                return i    
+            
+        # Time Complexity: O(n) 
+        n = len(nums)
+        # calculate the sum of first n numbers
+        sum_val = n * (n + 1) // 2
+        return sum_val - sum(nums)
+