# Sum Of Even Numbers After Queries Problem

## Description

LeetCode Problem 985.

You are given an integer array 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.

Example 1:

 1 2 3 4 5 6 7 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.

Example 2:

 1 2 Input: nums = [1], queries = [[4,0]] Output: [0]

Constraints:

• 1 <= nums.length <= 10^4
• -10^4 <= nums[i] <= 10^4
• 1 <= queries.length <= 10^4
• -10^4 <= val_i <= 10^4
• 0 <= index_i < nums.length

## Sample C++ Code

 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 class Solution { public: vector sumEvenAfterQueries(vector& nums, vector>& queries) { int sum = 0; for (int i = 0; i < nums.size(); i++) { if (nums[i] % 2 == 0) { sum += nums[i]; } } vector ans; for (int i = 0; i < queries.size(); i++) { int val = queries[i][0]; int index = queries[i][1]; if (nums[index] % 2 == 0) { sum -= nums[index]; } nums[index] += val; if (nums[index] % 2 == 0) { sum += nums[index]; } ans.push_back(sum); } return ans; } };