solves #2652: Sum Multiples in java

Author: anishLearnsToCode

Diff for: README.md

@@ -817,7 +817,7 @@
 | 2643 | [Row With Maximum Ones](https://leetcode.com/problems/row-with-maximum-ones)                                                                                           |                                                                                     [![Java](assets/java.png)](src/RowWithMaximumOnes.java)                                                                                      |                                                                                                                                   |
 | 2644 | [Find the Maximum Divisibility Score](https://leetcode.com/problems/find-the-maximum-divisibility-score)                                                               |                                                                               [![Java](assets/java.png)](src/FindTheMaximumDivisibilityScore.java)                                                                               |                                                                                                                                   |
 | 2651 | [Calculate Delayed Arrival Time](https://leetcode.com/problems/calculate-delayed-arrival-time)                                                                         |                                                                                 [![Java](assets/java.png)](src/CalculateDelayedArrivalTime.java)                                                                                 |                                                                                                                                   |
-| 2652 | [Sum Multiples](https://leetcode.com/problems/sum-multiples)                                                                                                           |                                                                                                                                                                                                                                  |                                                                                                                                   |
+| 2652 | [Sum Multiples](https://leetcode.com/problems/sum-multiples)                                                                                                           |                                                                                        [![Java](assets/java.png)](src/SumMultiples.java)                                                                                         |                                                                                                                                   |
 | 2656 | [Maximum Sum With Exactly K Elements](https://leetcode.com/problems/maximum-sum-with-exactly-k-elements)                                                               |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2660 | [Determine the Winner of a Bowling Game](https://leetcode.com/problems/determine-the-winner-of-a-bowling-game)                                                         |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2670 | [Find the Distinct Difference Array](https://leetcode.com/problems/find-the-distinct-difference-array)                                                                 |                                                                                                                                                                                                                                  |                                                                                                                                   |

Diff for: src/SumMultiples.java

@@ -0,0 +1,19 @@
+// https://leetcode.com/problems/sum-multiples
+// T: O(1)
+// S: O(1)
+
+public class SumMultiples {
+    public int sumOfMultiples(int n) {
+        return 3 * summation(n / 3)
+                + 5 * summation(n / 5)
+                + 7 * summation(n / 7)
+                - 15 * summation(n / 15)
+                - 21 * summation(n / 21)
+                - 35 * summation(n / 35)
+                + 105 * summation(n / 105);
+    }
+
+    private int summation(int x) {
+        return (x * (x + 1)) / 2;
+    }
+}