The Binary Search Algorithm

1
The Binary Search Algorithm

• in
• Structured Flowchart Form
• Implemented in Both
• C/C and Java
• Bary W Pollack
• Dec. 28, 2001

2
Main
A array of int LTH length of A

3
Binary Search Flowchart

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C/C Main Routine

• //---------------------------------------//
  File BinarySearch.c//------------------------
  ---------------// Demonstrate the BinarySearch
  function//---------------------------------------
  include ltstdio.hgtint main (void) const
  int LTH 10 int i, nArray LTH1 int
  BinarySearch (const int v,
• const int a ,
• const int nLth)
  puts ("Demonstrate Binary Search\n")
• for (i 0 i lt LTH i) nArrayi
  i for (i -1 i lt LTH i)
  printf ("3d is at d\n",
• i,
• BinarySearch (i, nArray, LTH))
• puts ("\nFin!") return (0)

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C/C Binary Search Fcn

• //--------------------------------------------
• // Binary Search Algorithm
• // Divide the remaining table in half
• // Check the midpoint if found, DONE
• // If not found, consider the first half
• // or second half, depending...
• // and do Binary Search on it
• // If the partition size goes to ONE, the
• // item is NOT present in the table
• //--------------------------------------------
• int BinarySearch (const int nKey,
• const int nArray ,
• const int nLth)
• int nLoc -1, nLow 0, nHigh nLth-1
• while (nHigh gt nLow)
• int m (nLow nHigh) / 2
• if (nKey nArray m)

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C/C Program Output

• Demonstrate Binary Search
• -1 is at -1
• 0 is at 0
• 1 is at 1
• 2 is at 2
• 3 is at 3
• 4 is at 4
• 5 is at 5
• 6 is at 6
• 7 is at 7
• 8 is at 8
• 9 is at 9
• 10 is at -1
• Fin!

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Java Public Main Class

• // File BinarySearch.java
• // Demonstrate the binarySearch method
• public class BinarySearch
• BinarySearch(int nArray)
• for (int i 0 i lt nArray.length i)
• nArrayi i
• for (int i -1 i lt nArray.length i)
• System.out.println(i " is at "
• binarySearch(i, nArray))
• public static void main(String args)
• System.out.println("Demonstrate "
• "Binary Search")
• System.out.println()
• new BinarySearch(new int10
• System.out.println()

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Java Binary Search Method

• //--------------------------------------------
• // Binary Search Algorithm
• // Divide the remaining table in half
• // Check the midpoint if found, DONE
• // If not found, consider the first half
• // or second half, depending...
• // and do Binary Search on it
• // If the partition size goes to ONE, the
• // item is NOT present in the table
• //--------------------------------------------
• int binarySearch (final int nKey,
• final int nArray )
• int nLoc-1, nLow0, nHighnArray.length-1
• while (nHigh gt nLow)
• int m (nLow nHigh) / 2
• if (nKey nArray m)
• nLoc m break
• if (nKey lt nArray m)
• nHigh m - 1

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Java Program Output

• Demonstrate Binary Search
• -1 is at -1
• 0 is at 0
• 1 is at 1
• 2 is at 2
• 3 is at 3
• 4 is at 4
• 5 is at 5
• 6 is at 6
• 7 is at 7
• 8 is at 8
• 9 is at 9
• 10 is at -1
• Fin!

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