Initial commit

Author: Sunmit Girme

TwoSum.java

@@ -0,0 +1,53 @@
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ *
+ * Created by sunmit9 on 30/03/17.
+ *
+ * https://leetcode.com/problems/two-sum
+ *
+ * Given an array of integers, return indices of the two numbers such that they add up to a specific target.
+ * You may assume that each input would have exactly one solution, and you may not use the same element twice.
+ *
+ * Given nums = [2, 7, 11, 15], target = 9,
+ * Because nums[0] + nums[1] = 2 + 7 = 9,
+ * return [0, 1].
+ *
+ */
+public class TwoSum {
+
+    public static void main(String[] args) {
+        int[] sol = twoSum(new int[]{2,7,11,15}, 9);
+        System.out.println(sol[0] + ", " + sol[1]);
+    }
+
+    public static int[] twoSum(int[] numbers, int target) {
+        int[] result = new int[2];
+        Map<Integer, Integer> map = new HashMap<>();
+        for (int i = 0; i < numbers.length; i++) {
+            map.put(numbers[i], i );
+            int complement = target - numbers[i+1];
+            if (map.containsKey(complement)) {
+                result[1] = i + 1;
+                result[0] = map.get(complement);
+                return result;
+            }
+        }
+        return result;
+    }
+
+    public int[] twoSums(int[] numbers, int target) {
+        int[] result = new int[2];
+        Map<Integer, Integer> map = new HashMap<Integer, Integer>();
+        for (int i = 0; i < numbers.length; i++) {
+            if (map.containsKey(target - numbers[i])) {
+                result[1] = i;
+                result[0] = map.get(target - numbers[i]) - 1;
+                return result;
+            }
+            map.put(numbers[i], i + 1);
+        }
+        return result;
+    }
+}