From c6dac7c413a92d401c583499f2892e58b083047e Mon Sep 17 00:00:00 2001
From: Ashkrit <ashkrit@gmail.com>
Date: Sun, 28 Jun 2015 18:24:43 +0800
Subject: [PATCH] Create TargetSum.java

---
 target_sum/solutions/TargetSum.java | 39 +++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 target_sum/solutions/TargetSum.java

diff --git a/target_sum/solutions/TargetSum.java b/target_sum/solutions/TargetSum.java
new file mode 100644
index 0000000..e3ece8f
--- /dev/null
+++ b/target_sum/solutions/TargetSum.java
@@ -0,0 +1,39 @@
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+
+public class TargetSum {
+
+    public boolean hasPair(int[] values, int expectedSum) {
+        Arrays.sort(values);
+        int left = 0;
+        int right = values.length - 1;
+
+        for (; left < right; ) {
+            int actualSum = values[left] + values[right];
+            if (actualSum > expectedSum) {
+                right--;
+            } else if (actualSum < expectedSum) {
+                left++;
+            } else {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public boolean hasPairUsingSet(int[] values, int expectedSum) {
+
+        Set<Integer> seenValues = new HashSet<>();
+        for (int value : values) {
+            int diff = expectedSum - value;
+            if (!seenValues.contains(diff)) {
+                seenValues.add(value);
+            } else {
+                //Found it is diffvalue & currvalue that wil make up sum
+                return true;
+            }
+        }
+        return false;
+    }
+}