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Tested Python solution for LeetCode 985 with 18 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 985 # by problem number
lcpy gen -s sum_even_after_queries # by problem name
nums and an array queries where queries[i] = [val_i, index_i].
For each query i, first, apply nums[index_i] = nums[index_i] + val_i, then print the sum of the even values of nums.
Return an integer array answer where answer[i] is the answer to the i-th query.
Input: nums = [1,2,3,4], queries = [[1,0],[-3,1],[-4,0],[2,3]]
Output: [8,6,2,4]
Explanation: At the beginning, the array is [1,2,3,4].
After adding 1 to nums[0], the array is [2,2,3,4], and the sum of even values is 2 + 2 + 4 = 8.
After adding -3 to nums[1], the array is [2,-1,3,4], and the sum of even values is 2 + 4 = 6.
After adding -4 to nums[0], the array is [-2,-1,3,4], and the sum of even values is -2 + 4 = 2.
After adding 2 to nums[3], the array is [-2,-1,3,6], and the sum of even values is -2 + 6 = 4.
Input: nums = [1], queries = [[4,0]]
Output: [0]
class Solution:
# Time: O(n + q)
# Space: O(q)
def sum_even_after_queries(self, nums: list[int], queries: list[list[int]]) -> list[int]:
even_sum = sum(num for num in nums if num % 2 == 0)
result: list[int] = []
for val, index in queries:
if nums[index] % 2 == 0:
even_sum -= nums[index]
nums[index] += val
if nums[index] % 2 == 0:
even_sum += nums[index]
result.append(even_sum)
return result
| Time | Space |
|---|---|
| O(n + q) | O(q) |