Binary Find (Java) (Edge Learning Edge Update)

Source: Internet
Author: User

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1 classArrayTest32 {3      Public Static voidMain (string[] args)4     {5         //int [] arr=new int[]{54,45,6,5,34,656,34,2};6         //int Index=getindex (arr,2);7         //System.out.println ("index=" +index);8 9         int[] arr1=New int[]{2,4,5,7,12,34,35,46,67,89,99};Ten         intIndex1=halfsearch (arr1,34); OneSystem.out.println ("index1=" +index1); A         intIndex2=halfsearch_2 (arr1,34); -System.out.println ("index2=" +index2); -     } the     /* - binary Find the main idea: - when the value you are looking for (key) is greater than the middle value (Arr[mid]), the subscript (min) of the minimum value becomes the intermediate value subscript plus 1 (mid+1) . - If the value you are looking for is less than the median value, the subscript (max) of the largest value becomes the median subscript minus 1 (mid-1). + Returns the mid-value subscript after the lookup, otherwise returns-1.  -     */ +     //binary Lookup is more efficient, but only if the array must be ordered A      Public Static intHalfsearch (int[] arr,intkey) at     { -         intMin=0,max=arr.length-1, mid; -          -          while(Min<max)//Jumps out of the loop when the subscript of the smallest value is greater than the maximum value, indicating that the specified value is not found -         { -Mid= (Min+max)/2; in             if(key>Arr[mid]) -Min=mid+1; to             Else if(key<Arr[mid]) +Max=mid-1; -             Else  the                 returnmid; *         } $         return-1;Panax Notoginseng     } -  the     //Another kind of binary sort of idea +      Public Static intHalfsearch_2 (int[] arr,intkey) A     { the         intMin=0,max=arr.length-1, mid; +Mid= (Min+max)/2; -          while(Arr[mid]!=key)//The value is not equal to the value specified, which means that the value cannot be found (not present) $         { $Mid= (Min+max)/2; -             if(key>Arr[mid]) -Min=mid+1; the             Else if(key<Arr[mid]) -Max=mid-1;Wuyi             if(min>max) the                 return-1; -Mid= (Min+max)/2; Wu         } -             returnmid; About     } $  -  -  -     //find the position where the array value first appears for the key A      Public Static intGetIndex (intarr [],intkey) +     { the          for(inti=0;i<arr.length;i++) -         { $             if(arr[i]==key) the                 returni; the         } the         return-1; the     } -}

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Binary Find (Java) (Edge Learning Edge Update)

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