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.
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. 20. The system of claim 18 , wherein determining the minimum weight of the deleted word with respect to segmented words in the target string comprises: determining a plurality of weights of the deleted word with respect to the segmented words in a first target string of a plurality of target strings based on the mapping of word pairs and their respective weights; calculating the minimum weight of the deleted word with respect to the respective segmented words in the first target string as ∑ d = 1 p ⁢ w D = ∑ d = 1 p ⁢ min i = 1 q ⁢ w ⁡ ( T i , D d ) , wherein W denotes weight, T i denotes the i th segmented word in the first target string, q denotes the number of segmented words in the target string, D d denotes the d th segmented word in the deleted word, and p denotes the number of deleted segmented words.