Update Data Structures and Algorithms.md

Author: MuruganViswanathan

Data Structures and Algorithms.md

@@ -83,18 +83,23 @@ std::vector<int> v;
 // General Operations
 //---------------------------------
 
+// Size
+unsigned int size = v.size();
+
 // Insert head, index, tail
 v.insert(v.begin(), value);             // head
 v.insert(v.begin() + index, value);     // index
 v.push_back(value);                     // tail
 
 // Access head, index, tail
 int head = v.front();       // head
+head = v[0];                // or using array style indexing
+
 int value = v.at(index);    // index
-int tail = v.back();        // tail
+value = v[index];           // or using array style indexing
 
-// Size
-unsigned int size = v.size();
+int tail = v.back();        // tail
+tail = v[v.size()-1];       // or using array style indexing
 
 // Iterate
 for(std::vector<int>::iterator it = v.begin(); it != v.end(); it++) {