The present invention relates to an algorithm that retrieves only k data elements having the largest (or smallest) key values from a dataset (i.e., top-k results) in a time linearly proportional to the size of the dataset. The proposed method using the algorithm finds the top-k results using a k-sized min (or max) heap structure that maintains candidate elements of the top-k results by scanning all data elements in the dataset only once. In other words, the present invention provides a linear-time top-k sort method that finds top-k results in a time linearly proportional to the size of the dataset (i.e., O(n) time complexity), while conventional sort algorithms for finding top-k results cannot find the top-k results in a time linearly proportional to the size of the dataset (i.e., at least O(n log n) time complexity).