When you read a long document, there is a good chance that many words occur multiple times. Instead of storing each word, it may be beneficial to only store unique words, and to represent the document as a vector of pointers to the unique words. Write a program that implements this strategy. Read a word at a time from cin. Keep a vector of words. If the new word is not contained in this vector, allocate memory, copy the word into it, and append a pointer to the new memory. If the word is already present, then append a pointer to the existing word. Hint: use new to dynamically allocate new words and obtain pointers to them.