#include <iostream>
#include <string>
#include <conio>
#include <iomanip>
#include <fstream>
using namespace std;

const MaxListSize = 1000;

int main() {
	int List[MaxListSize];
	int ListSize = 0;

	// extract the list
	ifstream myin("sorted.dat");
	if (!myin) {
		cerr << "Cannot open input file" << endl;
		return 1;
	}
	for (int i = 0; (i < MaxListSize) && (myin >> List[i]); ++i) {
		++ListSize;
	}

	// get the key
	cout << "Enter key value: ";
	int key;
	cin >> key;
	cout << endl;

	// perform the binary search
	int comparisons = 0;  // number of comparisons so far
	int left = 0;
	int right = ListSize - 1;
	int spot = ListSize;  // spot is where the value can be found, we are
	                      // guessing its not there
	while (left <= right) {
		int p = (left + right) / 2;
		cout << "Index range: " << setw(4) << left << " .. "
		 << setw(4) << p << " .. "
		 << setw(4) << right << " has value range: " << setw(4) << List[left]
		 << " .. " << setw(4) << List[p]  << setw(4) << " .. " << setw(4)
		 << List[right] << endl;

		// determine which half of the range the key is in
		if (key == List[p]) {
			// found it
			++comparisons;
			spot = p;
			break;
		}
		else if (key < List[p]) {
			// key cannot be in right half
			++comparisons;   // one for the if test
			++comparisons;   // one for the else if test
			right = p - 1;
		}
		else {
			// key cannot be in left half
			++comparisons;   // one for the if test
			++comparisons;   // one for the else if test (which brought us here)
			left = p + 1;
		}
	}

	// display search results
	cout << endl;
	if ((spot < ListSize) && (List[spot] == key)) {
		cout << "Found " << key << ".\n" << endl
		 << "Number of comparisons required: "
		 << comparisons << " to process list of size " << ListSize << endl;
	}
	else {
		cout << "Did not find " << key << ".\n" << endl
		 << "Number of comparisons required: "
		 << comparisons << " to process list of size " << ListSize << endl;
	}

	// we are all done
	getch();
	return 0;
}