#include <iostream>
#include <cmath>      // std::round(...)

// Query the user for a floating-point grade between 0 and 100,
// inclusive, and assign it to 'grade'. If the grade is outside
// this range, print "Invalid grade" and return -1.
//
// First, determine and display the corresponding letter grade
// according to the following rules:
//
//     grade < 50             F
//     50 <= grade < 60       D
//     60 <= grade < 70       C
//     70 <= grade < 80       B
//     80 <= grade < 90       A
//     90 <= grade            A+
//
// Next, calculate the corresponding grade-point value on a
// scale from 0.0 to 4.0.
//
// Some universities convert percentage grades into grade points,
// which are then averaged to calculate a grade-point average
// (GPA). Thus, the value calculated in this exercise is the grade
// point for one grade; a GPA is the average of the grade points
// from multiple courses.
//
// For this exercise, use the following simplified approximation:
//
//     grade < 50             grade point = 0.0
//     50 <= grade < 95       convert the grade linearly
//     95 <= grade            grade point = 4.0
//
// For grades from 50 up to 95, the grade-point value increases
// linearly from 0.0 to 4.0. Assign the calculated grade-point
// value to the floating-point variable 'ans'.
//
// Display the grade-point value rounded to one decimal place
// using
//
//     std::round( 10.0*ans )/10.0
//
// Hint:
//
// For the letter grade, consider testing the boundaries from
// highest to lowest. If you have already determined that the
// grade is less than 90, for example, then when you test whether
// it is at least 80, you do not also have to test that it is
// less than 90.
//
// For the grade-point value between 50 and 95, first subtract 50
// so that a grade of 50 corresponds to 0. Then determine what
// factor will make a grade of 95 correspond to 4.0.

int main();

int main() {

    // This rounds 10*gpv to an integer, and then divides by 10.
    //   - For example, if gpv == 3.7293, then 10*gpv == 34.793,
    //     which rounds to 35, and divided by 10 yeilds 3.5
    std::cout << "The grade-point value is "
              << std::round( 10.0*gpv )/10.0
              << "." << std::endl;
    return 0;
}


















































/*
 * Solution:
 *
 * #include <iostream>
 * #include <cmath>
 *
 * int main();
 *
 * int main() {
 *     int grade{};
 *
 *     std::cout << "Enter a grade: ";
 *     std::cin  >> grade;
 *
 *     if ( grade < 0.0 || grade > 100.0 ) {
 *         std::cout << "Invalid grade" << std::endl;
 *         return -1;
 *     }
 *
 *     std::cout << "The letter grade is ";
 *
 *     if ( grade >= 90.0 ) {
 *         std::cout << "A+";
 *     } else if ( grade >= 80.0 ) {
 *         std::cout << "A";
 *     } else if ( grade >= 70.0 ) {
 *         std::cout << "B";
 *     } else if ( grade >= 60.0 ) {
 *         std::cout << "C";
 *     } else if ( grade >= 50.0 ) {
 *         std::cout << "D";
 *     } else {
 *         std::cout << "F";
 *     }
 *
 *     std::cout << "." << std::endl;
 *
 *     double gpv{};
 *
 *     if ( grade >= 95 ) {
 *         gpv = 4.0;
 *     } else if ( grade >= 50 ) {
 *         gpv = (grade - 50.0)*4.0/45.0;
 *     } else {
 *         gpv = 0.0;
 *     }
 *
 *     std::cout << "The grade-point value is "
 *               << std::round( 10.0*gpv )/10.0
 *               << "." << std::endl;
 *
 *     return 0;
 * }
 */