Глава_03

Birthdays () {

HistGraf Hist = new HistGraf (60, 30);
// The headings
System.out.println("");
System.out.println(" Probably of coincidence of Birthday ");
System.out.println("===================================");

System.out.println("Peoples \t \t Probably");

// Display a bar for each year and then the final axis
for (int year = 10; year <= Hist.label; ) {

Hist.bar(year, Proba(year)*50 );
year = year+10;

}
Hist.axis ();

}

// All programs must have a main method
public static void main (String [ ] args) {

// Start the program running from its constructor
new Birthdays();

}

double Proba(int n){

int m = 365;
double k = 1;
double p = 0;
for(int i=0; i < n; i++){

k = k*(m-i)/m;

}
p = 1 - k;
return p;

}

int label;
int h;

HistGraf (int l, int c) {

label = l;
h = c;

}
void bar(int label, double h) {

// Draws a single histogram bar labelled
// with the years and consisting of the given
// number of stars
System.out.print(label+" peoples \t|");
int stop = (int) Math.round(h);
for (int star = 0; star < stop; star++)
System.out.print('*');
// System.out.println(" " + (double) h/100);
System.out.println(" " + Stream.format((double) h*2,3,2));

}

void axis () {

// Draws a horizontal axis with ticks+1 divisions
// labelled in steps of 10. Each division is 10
// characters wide.

int ticks = 5;

// Print the line
System.out.print("\t\t\t");
for (int line = 0; line < ticks*10; line++)
System.out.print("=");
System.out.println("=");

//Print the ticks
System.out.print("\t\t\t");
for (int n = 0; n < ticks; n++)
System.out.print("+ ");
System.out.println('+');
// Label the ticks, including the last one
System.out.print("\t\t\t");
for (int n = 0; n <= ticks; n++)
System.out.print(n*20 + " ");
System.out.println();

// Label the whole axis
System.out.println("\t\t\t\t percent");

}