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The Binary Search Algorithm

This document showcases the Binary Search algorithm implemented in both C/C++ and Java. The algorithm is presented in a clear flowchart format, illustrating the divide-and-conquer strategy used to locate elements within a sorted array. The implementation includes a demonstration program that shows how to search for integers in an array, printing their respective locations. The flowchart and code snippets are tailored for learners and developers seeking to understand and apply binary search effectively.

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The Binary Search Algorithm

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  1. The Binary Search Algorithm in Structured Flowchart Form Implemented in Both C/C++ and Java Bary W Pollack Dec. 28, 2001

  2. Main Main Print “Demonstrate Binary Search” For i = 0 thru LTH-1 by 1 A [i] = i For i = -1 thru LTH by 1 Print “i is at BinarySearch (i, A, LTH )” Print “Fin!” Return 0 A = array of int LTH = length of A

  3. Binary Search Flowchart BinarySearch (Key, A, LTH) Locn = -1 Lo = 0 Hi = LTH - 1 While Hi > Lo m = (Lo + Hi) / 2 Key = A[m] Locn = m Break Key < A[m] Hi = m-1 Lo = m+1 Return Locn

  4. C/C++ Main Routine //---------------------------------------// File: BinarySearch.c//---------------------------------------// Demonstrate the BinarySearch function//---------------------------------------#include <stdio.h>int main (void){ const int LTH = 10; int i, nArray [LTH+1]; int BinarySearch (const int v, const int a [], const int nLth); puts ("Demonstrate Binary Search\n"); for (i = 0; i < LTH; i++) nArray[i] = i; for (i = -1; i <= LTH; i++) printf ("%3d is at %d\n", i, BinarySearch (i, nArray, LTH)); puts ("\nFin!"); return (0);}

  5. 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 >= nLow) { int m = (nLow + nHigh) / 2; if (nKey == nArray [m]) { nLoc = m; break; } if (nKey < nArray [m]) nHigh = m - 1; else nLow = m + 1; } return nLoc; }

  6. 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!

  7. Java Public Main Class // File: BinarySearch.java // Demonstrate the binarySearch method public class BinarySearch { BinarySearch(int[] nArray) { for (int i = 0; i < nArray.length; i++) nArray[i] = i; for (int i = -1; i <= 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 int[10] System.out.println(); System.out.println("Fin!"); }

  8. 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, nLow=0, nHigh=nArray.length-1; while (nHigh >= nLow) { int m = (nLow + nHigh) / 2; if (nKey == nArray [m]) { nLoc = m; break; } if (nKey < nArray [m]) nHigh = m - 1; else nLow = m + 1; } return nLoc; }

  9. 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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