[LEET-3318] add 3318

Author: fishercoder1534

Diff for: paginated_contents/algorithms/4th_thousand/README.md

@@ -1,5 +1,6 @@
 | #    | Title                                                                                                                                                               | Solutions                                                                                                                         | Video                                                                         | Difficulty | Tag                                                                  
 |------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------|------------|----------------------------------------------------------------------
+| 3318 | [Find X-Sum of All K-Long Subarrays I](https://leetcode.com/problems/find-x-sum-of-all-k-long-subarrays-i/)                                                                 | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/fourththousand/_3318.java) |                                                                               | Easy       |
 | 3285 | [Find Indices of Stable Mountains](https://leetcode.com/problems/find-indices-of-stable-mountains/)                                                                 | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/fourththousand/_3285.java) |                                                                               | Easy       |
 | 3264 | [Final Array State After K Multiplication Operations I](https://leetcode.com/problems/final-array-state-after-k-multiplication-operations-i/)                                                                 | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/fourththousand/_3264.java) |                                                                               | Easy       |
 | 3263 | [Convert Doubly Linked List to Array I](https://leetcode.com/problems/convert-doubly-linked-list-to-array-i/)                                                                 | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/fourththousand/_3263.java) |                                                                               | Easy       |

Diff for: src/main/java/com/fishercoder/solutions/fourththousand/_3318.java

@@ -0,0 +1,53 @@
+package com.fishercoder.solutions.fourththousand;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.PriorityQueue;
+
+public class _3318 {
+    public static class Solution1 {
+        public int[] findXSum(int[] nums, int k, int x) {
+            PriorityQueue<int[]> maxHeap = new PriorityQueue<>((a, b) -> a[1] != b[1] ? b[1] - a[1] : b[0] - a[0]);//a[0] is the number itself, a[1] is the frequency
+            Map<Integer, int[]> map = new HashMap<>();
+            int i = 0;
+            for (; i < k; i++) {
+                int[] a = map.getOrDefault(nums[i], new int[2]);
+                a[0] = nums[i];
+                a[1]++;
+                map.put(nums[i], a);
+            }
+            maxHeap.addAll(map.values());
+            int[] ans = new int[nums.length - k + 1];
+            for (int j = i - 1, p = 0; j < nums.length; ) {
+                ans[p++] = computeTopX(new PriorityQueue<>(maxHeap), x);
+
+                j++;
+                if (j >= nums.length) {
+                    break;
+                }
+                int[] a = map.getOrDefault(nums[j], new int[2]);
+                a[0] = nums[j];
+                a[1]++;
+                map.put(nums[j], a);
+
+                a = map.getOrDefault(nums[j - k], new int[2]);
+                a[0] = nums[j - k];
+                a[1]--;
+                map.put(nums[j - k], a);
+
+                maxHeap.clear();
+                maxHeap.addAll(map.values());
+            }
+            return ans;
+        }
+
+        private int computeTopX(PriorityQueue<int[]> maxHeap, int x) {
+            int sum = 0;
+            while (!maxHeap.isEmpty() && x-- > 0) {
+                int[] a = maxHeap.poll();
+                sum += a[0] * a[1];
+            }
+            return sum;
+        }
+    }
+}

Diff for: src/test/java/com/fishercoder/fourththousand/_3318Test.java

@@ -0,0 +1,30 @@
+package com.fishercoder.fourththousand;
+
+import com.fishercoder.solutions.fourththousand._3318;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+public class _3318Test {
+
+    private _3318.Solution1 solution1;
+    private static int[] nums;
+
+    @BeforeEach
+    public void setup() {
+        solution1 = new _3318.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        nums = new int[]{1, 1, 2, 2, 3, 4, 2, 3};
+        assertArrayEquals(new int[]{6, 10, 12}, solution1.findXSum(nums, 6, 2));
+    }
+
+    @Test
+    public void test2() {
+        nums = new int[]{3, 8, 7, 8, 7, 5};
+        assertArrayEquals(new int[]{11, 15, 15, 15, 12}, solution1.findXSum(nums, 2, 2));
+    }
+}