Added a better way of Sequential search to existing file

Author: Gurs

Algorithm/SequentialSearch.h

@@ -4,4 +4,20 @@ int SequentialSearch(vector<int>& v, int k) {
 		if (v[i] == k)
 			return i;
 	return -1;
+}
+
+
+/* The following is a Sentinel Search Algorithm which only performs 
+    just one test in each loop iteration thereby reducing time complexity */
+
+int BetterSequentialSearch(vector<int>& v, int k) {
+    int last = v[v.size()-1];
+    v[v.size()-1] = k;
+    int i = 0;
+	while (v[i]!= k)
+        	i++;
+    v[v.size()-1] = last;
+    if(i < v.size()-1 || v[v.size()-1] == k)
+        return i;
+    return -1;
 }