An inverted file is a critical data structure for implementing index of book or central components of a search engine. Given document D, which can be viewed as an un-ordered numbered list of words, an inverted file is an ordered list of words L, such that, for each word w in L, we store the indices of the places in D where w appears. Design an efficient algorithm using ONLY pseudocode for constructing L from D and an efficient underlying data structure. (This problem requires only pseudocode and not actual code).