Add 981_Time_Based_Key-Value_Store.java

Author: Sean Prashad

Design/981_Time_Based_Key-Value_Store.java

@@ -0,0 +1,51 @@
+class TimeMap {
+    private Map<String, List<Node>> hm;
+
+    public TimeMap() {
+        hm = new HashMap<>();
+    }
+
+    public void set(String key, String value, int timestamp) {
+        hm.putIfAbsent(key, new ArrayList<>());
+        hm.get(key).add(new Node(timestamp, value));
+    }
+
+    public String get(String key, int timestamp) {
+        if (!hm.containsKey(key)) {
+            return "";
+        }
+
+        List<Node> nodes = hm.get(key);
+        int low = 0, high = nodes.size() - 1;
+
+        while (low < high) {
+            int mid = low + (high - low) / 2;
+
+            if (nodes.get(mid).timestamp == timestamp) {
+                return nodes.get(mid).value;
+            }
+
+            if (nodes.get(mid).timestamp < timestamp) {
+                if (nodes.get(mid + 1).timestamp > timestamp) {
+                    return nodes.get(mid).value;
+                }
+
+                low = mid + 1;
+            } else {
+                high = mid - 1;
+            }
+        }
+
+        return nodes.get(low).timestamp <= timestamp ? nodes.get(low).value : "";
+    }
+
+    private class Node {
+        private int timestamp;
+        private String value;
+
+        public Node(int t, String v) {
+            timestamp = t;
+            value = v;
+        }
+    }
+}