A new global search method for general contact systems is developed and implemented in the DYNA3D program, along with a recent contact interface algorithm. The concept of `position codes' for efficient global contact searching is presented. With the position code algorithm, the problem of sorting and searching in three dimensions is transformed to a process of sorting and searching within a one-dimensional array. The cost of contact searching is of the order of N log2 N, where N is the number of nodes in the system. The proposed algorithms are uncomplicated and the implementation into any finite element code is straightforward. Numerical experiments are presented in order to examine the behaviour of the algorithms in different aspects.