在一些有N个元素的集合应用问题中，我们通常是在开始时让每个元素构成一个单元素的集合，然后按一定顺序将属于同一组的元素所在的集合合并，其间要反复查找一个元素在哪个集合中。这一类问题近几年来反复出现在信息学的国际国内赛题中，其特点是看似并不复杂，但数据量极大，若用正常的数据结构来描述的话，往往在空间上过大，计算机无法承受；即使在空间上勉强通过，运行的时间复杂度也极高，根本就不可能在比赛规定的运行时间（1～3秒）内计算出试题需要的结果，只能采用一种全新的抽象的特殊数据结构——并查集来描述。-N elements in the collection of application problems, we are usually at the beginning of each element to constitute a single element of the collection, and the merger of the collection belonging to the same group of elements certain order, was to be repeated to find an element in which the collection. This type of problem in recent years recurring domestic and international race title Informatics, which is characterized by a seemingly is not complicated, but the amount of data, normal data structures described, often in the space is too large , the computer can not afford　narrowly passed even in space, running time complexity is also very high, simply impossible questions need to calculate the results of the competition provisions of the running time (1-3 seconds), only a new abstract special data structure- and check set to describe.