TwoSummIII done

Author: rampatra

src/main/java/com/leetcode/arrays/NestedListWeightSumII.java

@@ -64,7 +64,6 @@ public static void main(String[] args) {
         assertEquals(0, nestedSum(Collections.singletonList(new NestedInteger().add(new NestedInteger()))));
 
         // TODO: fix the test cases
-
         // {2, {1,1}, {1,1}}
         NestedInteger ni = new NestedInteger(2);
         ni.add(new NestedInteger().add(new NestedInteger(1)).add(new NestedInteger(1)));

src/main/java/com/leetcode/maps/TwoSumIII.java

@@ -0,0 +1,78 @@
+package com.leetcode.maps;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Level: Easy
+ * Problem Link: https://leetcode.com/problems/two-sum-iii-data-structure-design/
+ * Problem Description:
+ * Design and implement a TwoSum class. It should support the following operations: add and find.
+ * <p>
+ * add - Add the number to an internal data structure.
+ * find - Find if there exists any pair of numbers which sum is equal to the value.
+ * <p>
+ * Example 1:
+ * add(1); add(3); add(5);
+ * find(4) -> true
+ * find(7) -> false
+ * <p>
+ * Example 2:
+ * add(3); add(1); add(2);
+ * find(3) -> true
+ * find(6) -> false
+ *
+ * @author rampatra
+ * @since 2019-08-03
+ */
+public class TwoSumIII {
+
+    Map<Integer, Integer> numCount;
+
+    /**
+     * Initialize your data structure here.
+     */
+    public TwoSumIII() {
+        this.numCount = new HashMap<>();
+    }
+
+    /**
+     * Add the number to an internal data structure..
+     */
+    public void add(int number) {
+        if (numCount.containsKey(number)) {
+            numCount.put(number, 2);
+        } else {
+            numCount.put(number, 1);
+        }
+    }
+
+    /**
+     * Find if there exists any pair of numbers which sum is equal to the value.
+     */
+    public boolean find(int value) {
+        for (Map.Entry<Integer, Integer> entry : numCount.entrySet()) {
+            int num1 = entry.getKey();
+            int num2 = value - num1;
+            if ((num2 == num1 && entry.getValue() == 2) || (num1 != num2 && numCount.containsKey(num2))) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Runtime: <a href="https://leetcode.com/submissions/detail/248632458/">115 ms</a>.
+     *
+     * @param args
+     */
+    public static void main(String[] args) {
+        TwoSumIII twoSumIII = new TwoSumIII();
+        twoSumIII.add(0);
+        twoSumIII.add(-1);
+        twoSumIII.add(1);
+        assertTrue(twoSumIII.find(0));
+    }
+}