Data structure Tutorial 30th class static lookup table (ii) ordered table lookup

Teaching Purpose: grasping the binary search method of ordered table

Teaching Focus: binary search

Teaching Difficulty: binary search

Teaching Content:

Find process of binary lookup

When an ordered table represents a static lookup table, the search function can be implemented using binary lookup.

Determine the range (interval) in which the record is located, and then gradually narrow it down until the record is found or is not found.

Finding realization of Binary lookup

int Search_bin (sstable st,keytype key) {

Low=1;high=st.length;

while (Low<=high) {

Mid= (Low+high)/2;

If EQ (Key,st.elem[mid].key) return mid;

else if LT (Key,st.elem[mid].key) high=mid-1;

else Low=mid +1;

}

return 0;

}//search_bin;

Performance analysis of binary search

Binary find the number of keywords to compare with a given value when looking for success at most