Introduction - If you have any usage issues, please Google them yourself
Circular linked list to implement a two-way, each node in addition to prior, data and next 3 fields but also added a visit to the frequency domain freq. He was appointed in the list before the freq the frequency domain values are initialized to zero, but when the list was a LOCATE (L, x) after the operation, was visited node (ie element value is equal to the node x ) in the frequency domain freq will increase the value of 1, while modifying the list order between nodes, so that access to the frequency according to the order of non-increasing order, so always keep frequently accessed nodes are always close to the table head node.