Create 985_sum-of-even-numbers-after-queries.py

Author: stevestar888

985_sum-of-even-numbers-after-queries.py

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+"""
+https://leetcode.com/problems/sum-of-even-numbers-after-queries/
+
+O(n) / linear time — iteration over queries; all other operations are constant
+
+Runtime: 507 ms, faster than 98.92% of Python3 online submissions for Sum of Even Numbers After Queries.
+Memory Usage: 20.5 MB, less than 76.90% of Python3 online submissions for Sum of Even Numbers After Queries.
+"""
+class Solution:
+    def sumEvenAfterQueries(self, nums: List[int], queries: List[List[int]]) -> List[int]:
+        running_even_sum = sum(num for num in nums if num % 2 == 0)
+        res = list()
+        
+        # perform query operations
+        for query in queries:
+            value, idx = query
+            
+            if nums[idx] % 2 == 0:
+                running_even_sum -= nums[idx]
+            
+            nums[idx] += value
+            
+            if nums[idx] % 2 == 0:
+                running_even_sum += nums[idx]
+            
+            res.append(running_even_sum)
+            
+        return res