下面程序实现对递减有序的顺序表进行二分查找，请在空白处填写适当内容，使该程序功能完整。int BinSearch(SeqList R,intn,KeyType K){int low=1,high=n;while(low<=high){mid= (1) ;if(R[mid].key==K)return mid;if(R[mid].key>K)(2) ;else(3) ;}return 0;}