added problem 985

Java/SumOfEvenNumbersAfterQueries.java

@@ -0,0 +1,38 @@
+// link:  https://leetcode.com/problems/sum-of-even-numbers-after-queries/
+class SumOfEvenNumbersAfterQueries {
+    public int[] sumEvenAfterQueries(int[] nums, int[][] queries) {
+        int initialSum = 0;
+        for (int i : nums) {
+            if (i % 2 == 0) {
+                initialSum += i;
+            }
+        }
+        // System.out.println("init: " + initialSum);
+        int[] ans = new int[nums.length];
+        for (int i = 0; i < nums.length; i++) {
+            int oldValue = nums[queries[i][1]];
+            nums[queries[i][1]] += queries[i][0];
+            initialSum = evenSum(nums, queries[i][1], queries[i][0], nums[queries[i][1]], initialSum, oldValue);
+            // System.out.println(MessageFormat.format("oldValue = {0}, newValue = {1}, nums
+            // = {3}",oldValue,nums[queries[i][1]]));
+            // System.out.println(Arrays.toString(ans));
+            ans[i] = initialSum;
+        }
+        return ans;
+    }
+
+    private int evenSum(int[] arr, int modifiedIndex, int newValue, int modifiedValue, int initialSum, int oldValue) {
+        if (modifiedValue % 2 == 0) {
+            if (oldValue % 2 == 0) {
+                initialSum = initialSum - oldValue + modifiedValue;
+            } else {
+                initialSum = initialSum + modifiedValue;
+            }
+        } else {
+            if (oldValue % 2 == 0) {
+                initialSum -= oldValue;
+            }
+        }
+        return initialSum;
+    }
+}