985. Sum of Even Numbers After Queries

SumEvenAfterQueries.cs

public class Solution {
  public int[] SumEvenAfterQueries(int[] nums, int[][] queries) {
    var res = new int[nums.Length];
    var evenSum = 0;
    for(var j = 0; j < nums.Length; ++j){
      res[j] = nums[j];
      if(nums[j] % 2 == 0)
        evenSum += nums[j];
    }
      
    var i = 0;
    foreach(var query in queries){
      var num = nums[query[1]];
      
      nums[query[1]] += query[0];
      
      if(num % 2 == 0 && nums[query[1]] % 2 == 0){
        evenSum -= num;
        evenSum += nums[query[1]];
      }
      else if(num % 2 != 0 && nums[query[1]] % 2 == 0)
        evenSum += nums[query[1]];
      else if(num % 2 == 0 && nums[query[1]] % 2 != 0)
        evenSum -= num;
      
      res[i++] = evenSum;
    }
    return res;
  }
  public int[] SumEvenAfterQueriesBruteForce(int[] nums, int[][] queries) {
    var res = new int[nums.Length];
    for(var j = 0; j < nums.Length; ++j)
      res[j] = nums[j];
    var i = 0;
    foreach(var query in queries){
      nums[query[1]] += query[0];
      var evenSum = 0;
      for(var j = 0; j < nums.Length; j++)
        if(nums[j] % 2 == 0)
          evenSum += nums[j];
      res[i++] = evenSum; 
    }
    return res;
  }
}