add 2080

Author: fishercoder1534

README.md

@@ -8,6 +8,7 @@ _If you like this project, please leave me a star._ ★
 
 |  #  |      Title     |   Solutions   | Video  | Difficulty  | Tag                  
 |-----|----------------|---------------|--------|-------------|-------------
+|2080|[Range Frequency Queries](https://leetcode.com/problems/range-frequency-queries/)|[Java](../master/src/main/java/com/fishercoder/solutions/_2080.java) ||Medium|Array, Binary Seaarch|
 |2079|[Watering Plants](https://leetcode.com/problems/watering-plants/)|[Java](../master/src/main/java/com/fishercoder/solutions/_2079.java) ||Medium||
 |2078|[Two Furthest Houses With Different Colors](https://leetcode.com/problems/two-furthest-houses-with-different-colors/)|[Java](../master/src/main/java/com/fishercoder/solutions/_2078.java) ||Easy||
 |2076|[Process Restricted Friend Requests](https://leetcode.com/problems/process-restricted-friend-requests/)|[Java](../master/src/main/java/com/fishercoder/solutions/_2076.java) ||Hard||

src/main/java/com/fishercoder/solutions/_2080.java

@@ -0,0 +1,38 @@
+package com.fishercoder.solutions;
+
+import java.util.*;
+
+public class _2080 {
+    public static class Solution1 {
+
+        public static class RangeFreqQuery {
+            /**
+             * This post explains it well: https://leetcode.com/problems/range-frequency-queries/discuss/1589019/Java-or-Binary-Search-or-Log(n)-for-every-query
+             */
+
+            Map<Integer, List<Integer>> map;
+
+            public RangeFreqQuery(int[] arr) {
+                map = new HashMap<>();
+                for (int i = 0; i < arr.length; i++) {
+                    List<Integer> list = map.getOrDefault(arr[i], new ArrayList<>());
+                    list.add(i);
+                    map.put(arr[i], list);
+                }
+            }
+
+            public int query(int left, int right, int value) {
+                List<Integer> list = map.getOrDefault(value, new ArrayList<>());
+                int start = Collections.binarySearch(list, left);
+                int end = Collections.binarySearch(list, right);
+                if (start < 0) {
+                    start = (start + 1) * -1;
+                }
+                if (end < 0) {
+                    end = (end + 2) * -1;
+                }
+                return end - start + 1;
+            }
+        }
+    }
+}

src/test/java/com/fishercoder/_2080Test.java

@@ -0,0 +1,37 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._2080;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _2080Test {
+    private static _2080.Solution1.RangeFreqQuery rangeFreqQuery;
+
+    @Test
+    public void test1() {
+        rangeFreqQuery = new _2080.Solution1.RangeFreqQuery(new int[]{12, 33, 4, 56, 22, 2, 34, 33, 22, 12, 34, 56});
+        assertEquals(1, rangeFreqQuery.query(1, 2, 4));
+        assertEquals(2, rangeFreqQuery.query(0, 11, 33));
+    }
+
+    @Test
+    public void test2() {
+        rangeFreqQuery = new _2080.Solution1.RangeFreqQuery(new int[]{1, 1, 1, 2, 2});
+        assertEquals(0, rangeFreqQuery.query(0, 1, 2));
+        assertEquals(3, rangeFreqQuery.query(0, 2, 1));
+        assertEquals(1, rangeFreqQuery.query(3, 3, 2));
+        assertEquals(1, rangeFreqQuery.query(2, 2, 1));
+    }
+
+    @Test
+    public void test3() {
+        rangeFreqQuery = new _2080.Solution1.RangeFreqQuery(new int[]{3, 4, 5, 3, 3, 2, 2, 2, 5, 4});
+//        assertEquals(2, rangeFreqQuery.query(2, 6, 3));
+//        assertEquals(0, rangeFreqQuery.query(5, 6, 5));
+//        assertEquals(2, rangeFreqQuery.query(1, 6, 2));
+        assertEquals(1, rangeFreqQuery.query(0, 2, 3));
+        assertEquals(0, rangeFreqQuery.query(5, 6, 4));
+    }
+
+}