设有一个双向循环链表，每个结点中除有pre，data和next三个域外，还增设了一个访问频度域freq。在链表被起作用前，频度域freq的值均初始化为零，而当对链表进行一次LOCATE(L,x)的操作之后，被访问的结点（即元素值等于x的节点）中的频度域freq的值便增1，同时调整链表中结点之间的次序，使其按访问频度非递增的顺序排列，以便始终保持被频繁访问的结点总是靠近表头结点。-There is a two-way circular linked list, each node in addition to a pre, data and next three outside, but also the addition of a frequency-domain access freq. Before the list is to work, the value of the frequency domain freq are initialized to zero, and when on the list once LOCATE (L, x) after the operation, the node being accessed (ie, the elements of a node is equal to x) of freq the frequency domain value will be incremented by 1, and adjust the order of the list between nodes, making it non-access frequency increasing order to always keep the junction frequently accessed is always close to the header node.