18. A system for ranking search results, comprising: one or more processors configured to: receive a query string; retrieve a plurality of search results that include a corresponding plurality of target strings that relate to the query string; segment the query string and each of the plurality of target strings; determine, 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; determine, 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; determine 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 rank the plurality of target strings based on the total edit distances; and one or more memories coupled to the one or more processors, configured to provide the one or more processors with instructions.
19. The system of claim 18 , wherein determining a minimum weight of each inserted word with respect to segmented words in the query string comprises: determining the plurality of weights of the inserted word with respect to segmented words in the query string based on the mapping of word pairs and their respective weights; calculating the minimum weight of the inserted word with respect to the respective segmented words in the query string as ∑ t = 1 n ⁢ w I = ∑ t = 1 n ⁢ min j = 1 m ⁢ w ⁡ ( I t , Q j ) , wherein W denotes weight, I t denotes the t th segmented word in the inserted string, n denotes the number of inserted segmented words, Q j denotes the j th segmented word in the query string, and m denotes the number of segmented words in the query string.