7. A method for ranking search results, comprising: receiving a query string; retrieving a plurality of search results that include a corresponding plurality of target strings that relate to the query string; segmenting the query string and each of the plurality of target strings; determining, based on a mapping of word pairs and their respective weights, a minimum weight of each inserted word with respect to segmented words in the query string, wherein the minimum weight of each inserted word comprises a minimum weight selected from a plurality of weights corresponding to respective ones of a plurality of word pairs associated with the inserted word and the segmented words in the query string; determining, based on a mapping of word pairs and their respective weights, a minimum weight of each deleted word with respect to segmented words in the plurality of target strings; determining a total edit distance based at least in part on the minimum weight of each inserted word and the minimum weight of each deleted word; and ranking the plurality of target strings based on the total edit distances.
7. A method for ranking search results, comprising: receiving a query string; retrieving a plurality of search results that include a corresponding plurality of target strings that relate to the query string; segmenting the query string and each of the plurality of target strings; determining, based on a mapping of word pairs and their respective weights, a minimum weight of each inserted word with respect to segmented words in the query string, wherein the minimum weight of each inserted word comprises a minimum weight selected from a plurality of weights corresponding to respective ones of a plurality of word pairs associated with the inserted word and the segmented words in the query string; determining, based on a mapping of word pairs and their respective weights, a minimum weight of each deleted word with respect to segmented words in the plurality of target strings; determining a total edit distance based at least in part on the minimum weight of each inserted word and the minimum weight of each deleted word; and ranking the plurality of target strings based on the total edit distances. 10. The method of claim 7 , wherein determining the total edit distance comprises: calculating a plurality of total edit distances for the plurality of target strings as W Total =W I +W D , wherein W Total denotes the total edit distance, W I denotes the minimum weight of the inserted word with respect to segmented words in the query string, and W D denotes the minimum weight of the deleted word with respect to segmented words in one of the plurality of target strings.