Added missing P2Q3_Reducer.py file.

Thanks to @leebrian for the heads-up.  I somehow missed out committing
this file to GitHub.

Author: P7h

ProblemStatement2/Python/P2Q3_Reducer.py

@@ -0,0 +1,32 @@
+#!/usr/bin/python
+
+#  Write a MapReduce program which will display the number of hits for each different file on the Web site.
+
+import sys
+
+countTotal = 0
+oldKey = None
+
+# Loop around the data
+# It will be in the format key\tval
+#
+
+for line in sys.stdin:
+    data_mapped = line.strip().split("\t")
+    if len(data_mapped) != 2:
+        # Something has gone wrong. Skip this line.
+        continue
+
+    thisKey, thisCount = data_mapped
+
+    if oldKey and oldKey != thisKey:
+        print oldKey, "\t", countTotal
+        oldKey = thisKey;
+        countTotal = 0
+
+    oldKey = thisKey
+    countTotal += int(thisCount)
+
+if oldKey != None:
+    print oldKey, "\t", countTotal
+