Algorithm learning----binary search algorithm

About binary search, has been confused, finally after reading some information, summed up a more practical notation.

Http://www.cnblogs.com/huang1990/archive/2013/04/02/2995284.html

http://my.oschina.net/wangliannet/blog/140480

The general principle is that the interval rule form is the same, the interval is not duplicated, the value is not missed.

The unknown origin array is source[], the array dimension is size, and the digit key to be checked.

The principle of interval division: 1, left closed right closed division method [)

Head=0,tail=size,mid= (Head+tail)/2;

Total interval is [0,size]

Start Lookup, if (Key<source[mid]), in the first half of the search, interval order for [Head,mid]; that is Tail=mid

if (Key==source[mid]), the value is found and the interval is [Mid,mid]

if (Key>source[mid]), the second half of the search, the interval order is [mid+1,tail]; that is head=mid+1

The above three sections are exactly the same as the entire unknown origin interval.

2, left closed right closed division method []

Head=0,tail=size-1,mid= (Head+tail)/2;

The total interval is [0,size-1]

Start Lookup, if (Key<source[mid]), in the first half of the search, interval order for [head,mid-1]; that is tail=mid-1

if (Key==source[mid]), the value is found and the interval is [Mid,mid]

if (Key>source[mid]), the second half of the search, the interval order is [mid+1,tail]; that is head=mid+1

The above three sections are exactly the same as the entire unknown origin interval.

Isn't that a good thing to remember?

The following is the code of the C # implementation [] form:

Http://www.cnblogs.com/huang1990/archive/2013/04/02/2995284.html

Algorithm learning----binary search algorithm