TIme value based map

Author: nikoo28

src/main/java/leetcode/medium/TimeMap.java

@@ -0,0 +1,70 @@
+package leetcode.medium;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+
+class TimeStampedValue {
+  public int timestamp;
+  public String value;
+
+  public TimeStampedValue(int timestamp, String value) {
+    this.timestamp = timestamp;
+    this.value = value;
+  }
+}
+
+public class TimeMap {
+  Map<String, ArrayList<TimeStampedValue>> entriesByKey;
+
+  public TimeMap() {
+    // Constructor to initialize the TimeMap object
+    entriesByKey = new HashMap<>();
+  }
+
+  public void set(String key, String value, int timestamp) {
+    // Implementation for setting the value at a specific timestamp
+    if(!entriesByKey.containsKey(key)) {
+      entriesByKey.put(key, new ArrayList<>());
+    }
+    ArrayList<TimeStampedValue> timeStampedValues = entriesByKey.get(key);
+    timeStampedValues.add(new TimeStampedValue(timestamp, value));
+  }
+
+  public String get(String key, int timestamp) {
+    if(!entriesByKey.containsKey(key)) return "";
+
+    ArrayList<TimeStampedValue> timeStampedValues = entriesByKey.get(key);
+    Optional<TimeStampedValue> timeStamp =
+        binarySearchTimestamp(timeStampedValues, timestamp);
+    if(timeStamp.isEmpty()) {
+      return "";
+    }
+
+    return timeStamp.get().value;
+  }
+
+  private Optional<TimeStampedValue> binarySearchTimestamp(
+      ArrayList<TimeStampedValue> arr, int target) {
+    int left = 0, right = arr.size() - 1;
+    int matchIndex = -1;
+
+    while (left <= right) {
+      int mid = left + (right - left) / 2;
+      TimeStampedValue cur = arr.get(mid);
+      if(cur.timestamp <= target) {
+        matchIndex = mid;
+        left = mid + 1;
+      }
+      else {
+        right = mid - 1;
+      }
+    }
+
+    if(matchIndex == -1) {
+      return Optional.empty();
+    }
+    return Optional.of(arr.get(matchIndex));
+  }
+}

src/test/java/leetcode/medium/TimeMapTest.java

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+package leetcode.medium;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class TimeMapTest {
+
+  private final TimeMap timeMap;
+
+  TimeMapTest() {
+    timeMap = new TimeMap();
+  }
+
+  @Test
+  void testSetAndGet1() {
+    timeMap.set("foo", "bar", 1);
+    assertEquals("bar", timeMap.get("foo", 1));
+    assertEquals("bar", timeMap.get("foo", 3));
+  }
+
+  @Test
+  void testSetAndGet2() {
+    timeMap.set("foo", "bar", 1);
+    timeMap.set("foo", "baz", 2);
+    assertEquals("bar", timeMap.get("foo", 1));
+    assertEquals("baz", timeMap.get("foo", 2));
+    assertEquals("baz", timeMap.get("foo", 3));
+  }
+}