Create 170. Two Sum III - Data structure design.java

Author: futurus

170. Two Sum III - Data structure design.java

@@ -0,0 +1,38 @@
+public class TwoSum {
+    ArrayList<Integer> list;
+    HashMap<Integer, Integer> map;
+    
+    /** Initialize your data structure here. */
+    public TwoSum() {
+        list = new ArrayList<>();
+        map = new HashMap<>();
+    }
+    
+    /** Add the number to an internal data structure.. */
+    public void add(int number) {
+        if (!map.containsKey(number)) {
+            map.put(number, 1);
+        } else {
+            map.put(number, map.get(number) + 1);
+        }
+        list.add(number);
+    }
+    
+    /** Find if there exists any pair of numbers which sum is equal to the value. */
+    public boolean find(int value) {
+        for (Integer i : list) {
+            if (((i == value - i) && map.get(i) > 1)
+             || ((i != value - i) && map.containsKey(value-i))) {
+                return true;
+             }
+        }
+        return false;
+    }
+}
+
+/**
+ * Your TwoSum object will be instantiated and called as such:
+ * TwoSum obj = new TwoSum();
+ * obj.add(number);
+ * boolean param_2 = obj.find(value);
+ */