sorted set

Analysis of Heilongjiang Province, the whole industry chain development of forage, feed, set up industrial competitiveness evaluation index system, by calculating the various provinces on the domestic feed industry competitiveness situation sorted, and finally to promote industrial development in Heilongjiang Province feed solutions.

分析黑龙江省整个饲料产业链发展状况，建立饲料产业竞争力评价指标体系，通过计算对国内各省份的饲料产业竞争力情况进行排序，最后提出增强黑龙江省饲料产业竞争力的对策。

According to width-first-searching, the generation of partial reachable integer set is sorted by the sequence in diagonal order of reachable vectors, then sorted by reachable integers' value, 2k permutations is produced.

按照广度优先搜索依次求出的可达整数，可达整数对应的可达向量之间是符合对角线序的，然后，按照可达整数的大小排序就得到一组2~k元置换。