16. The system of claim 14 , wherein: the weighted word length is the weighted word length of the shortest sliding window; and determining the weighted word length from the weights and ranking the respective plurality of target strings comprises: calculating the weighted word lengths of the shortest sliding windows for the plurality of target strings based on minimum weights corresponding to plurality of target strings; and comparing the weighted word lengths of the shortest sliding windows of the plurality of target strings; wherein a target string with a smaller weighted word length is ranked more highly than a target string with a greater weighted word length.
16. The system of claim 14 , wherein: the weighted word length is the weighted word length of the shortest sliding window; and determining the weighted word length from the weights and ranking the respective plurality of target strings comprises: calculating the weighted word lengths of the shortest sliding windows for the plurality of target strings based on minimum weights corresponding to plurality of target strings; and comparing the weighted word lengths of the shortest sliding windows of the plurality of target strings; wherein a target string with a smaller weighted word length is ranked more highly than a target string with a greater weighted word length. 17. The system of claim 16 , wherein calculating the weighted lengths of the shortest sliding windows for the plurality of target strings based on the minimum weights is based on ∑ i = k h ⁢ W i = ∑ i = k h ⁢ min j = 1 m ⁢ w ⁡ ( T i , Q j ) , wherein W denotes weight, T i denotes i th segmented word in a target string, k and h respectively denote the starting and ending positions of the shortest sliding window of the target string, Q j denotes j th segmented word in the query string, and m denotes number of segmented words in the query string.