// CSE 143 Section Exercise
// Represents a time span of hours and minutes elapsed.
// Class invariant: minutes < 60

public class TimeSpan {
    private int hours;
    private int minutes;

    // Constructs a time span with the given interval.
    // pre: hours >= 0 && minutes >= 0
    public TimeSpan(int hours, int minutes) {
        this.hours = 0;
        this.minutes = 0;
        this.add(hours, minutes);
    }
    
    // Adds the given interval to this time span.
    // pre: hours >= 0 && minutes >= 0
    public void add(int hours, int minutes) {
        this.hours += hours;
        this.minutes += minutes;
        
        // convert each 60 minutes into one hour
        this.hours += this.minutes / 60;
        this.minutes = this.minutes % 60;
    }
    
    // Returns the number of hours represented by this time span.  Must be >= 0.
    public int getHours() {
        return hours;
    }
    
    // Returns the number of minutes represented by this time span, from 0-59.
    public int getMinutes() {
        return minutes;
    }

    // Returns a String for this time span such as "6h15m".
    public String toString() {
        return hours + "h" + minutes + "m";
    }
}