//COMPUTER SCIENCE 161.01
//WEDNESDAY APRIL 12th 2017
//BINARY SEARCH 


lastNames = new Array("Borbonie", "Clark", "Dickerson", "Fairchild", 
		      "Garcia", "Hardman",  "Hurdle", "Morris",
                      "Moss",  "Nottingham", "Ortiz",  "Parke", 
                      "Sadler", "Shaheen", "Smith");

firstNames  = new Array("Korbin", "Richard", "Jack", "Austin",  
                       "Alex", "Austin", "Gray", "Robert",
                        "Landon", "Will", "Austin", "Jordan",
                       "Miles", "Chandler", "Alex" );




desiredName = prompt("Enter the last name of the person you wish to greet:");

//OUR PROGRAM SHOULD TAKE ADVANTAGE OF THE FACT THAT THE lastNames ARRAY IS 
//IN ALPHABETICAL ORDER



N = lastNames.length;
desired = prompt("Enter last name of desired person: ");

first = 0;  
last = N-1;
found = false;

count = 0;  //to count loop iterations

while (first <= last && found == false) {

      mid = (first + last)/2;     

      alert("first = " + first + "  last = " + last + "  mid = " + mid);

      if (desired > lastNames[mid])
           first = mid + 1;
      else if (desired < lastNames[mid])
           last = mid - 1;
      else
           found = true; 

      count++;
}

if (found == true)
  alert("Happy Wednesday to " + firstNames[mid]);
else {
  alert("first = " + first + "  last = " + last);
  alert("Could not find " + desired);
}

 
//REPORT AT BOTTOM… 

count + " comparisons"