二分法查找算法

// Code for BinarySearch

int BinarySearch(IntArrayType IntArray, int Low, int High, int Target)

{

 int Mid, Difference;

 while (Low <= High)

 {

    Mid = (Low + High) / 2;

    Difference = IntArray[Mid] - Target;

    if (Difference == 0)         // IntArray[Mid] == Target

       return Mid;

    else if (Difference < 0)     // IntArray[Mid] < Target

       Low = Mid + 1;

    else

       High = Mid - 1;

 }

 return -1;   // If reach here, Target was not found.

}

//////////////////////////////

Value,{ 需要查找的数据 }

L{ 数据列表最低 },H{ 数据列表最高 },M { 临时保存中间值的变量 }:integer;

ValueList:List for Sorted Data;{ 数据列表，已经排序 }

Result:=-1;

if (Value<ValueList[L]) or (Value>ValueList[H]) then exit;

while L<=H do

begin

 M:=(L+H) div 2;

 if ValueList[M]=Value then

 begin

   Result :=M;

   Break;

 end else if ValueList[M]>Value then

    H:=M-1

 else

    L:=M+1;

end;