Question

Write and test a function in C++ that uses the binary search algorithm to search an array of sorted strings – use a do..while loop to allow user to perform multiple searches w/o terminating the program – see sample output below. Use this name array:

string names[SIZE] = { "Collins, Bill", "Smith, Bart", "Allen, Jim",

        "Griffin, Jim", "Stamey, Marty", "Rose, Geri", "Taylor, Terri",

        "Johnson, Jill", "Allison, Jeff", "Looney, Joe", "Wolfe, Bill",

        "James, Jean", "Weaver, Jim", "Pore, Bob", "Rutherford, Greg",

        "Javens, Renee", "Harrison, Rose", "Setzer, Cathy",

        "Pike, Gordon", "Holland, Beth" };

/* Sample output:

To search the 20-element array, enter a name: Jones, January

Name "Jones, January" not found in array

Search again? Y/N: y

To search the 20-element array, enter a name: Pore, Bob

Name "Pore, Bob" found at index 11

Search again? Y/N: y

To search the 20-element array, enter a name: Looney, Joe

Name "Looney, Joe" found at index 9

Search again? Y/N: y

To search the 20-element array, enter a name: Weaver, Jim

Name "Weaver, Jim" found at index 18

Search again? Y/N: n                                   */

Answer 1

#include<bits/stdc++.h>
using namespace std;

int binSearch(string names[], string name, int n)
{
   int l = 0, e = n-1, mid;
   while(l<=e)
   {
       mid = (l+e)/2;
       if(names[mid] == name)
           return mid;
       else if(names[mid] > name)
           e = mid-1;
       else
           l = mid+1;
   }
   return -1;
}

int main()
{
   string names[] = { "Collins, Bill", "Smith, Bart", "Allen, Jim",

"Griffin, Jim", "Stamey, Marty", "Rose, Geri", "Taylor, Terri",

"Johnson, Jill", "Allison, Jeff", "Looney, Joe", "Wolfe, Bill",

"James, Jean", "Weaver, Jim", "Pore, Bob", "Rutherford, Greg",

"Javens, Renee", "Harrison, Rose", "Setzer, Cathy",

"Pike, Gordon", "Holland, Beth" };
int n = sizeof(names)/sizeof(names[0]);
sort(names, names+n);
  
string s;
char c;
int ind;
  
do{
   cout<<"To search the 20-element array, enter a name: ";
   fflush(stdin);
   getline(cin, s);
   ind = binSearch(names, s, n);
   if(ind == -1)
       cout<<"Name "<<'"'<<s<<'"'<<" not found in array"<<endl;
   else
       cout<<"Name "<<'"'<<s<<'"'<<" found at index "<<ind<<endl;
   cout<<"Search again? Y/N: ";
   cin>>c;
   }while(c == 'y' || c == 'Y');
  
   return 0;
}