算法四 1.1

1.1.1

package ch1.ch1_1.pratice; public class P1_1_1{ public static void main(String[] args) { double aa = (0+15)/2; int a = (0 + 15) / 2; double b = Math.pow(2.0, -6) * 100000000.1; //Math.Pow(double x, double y) 求x的y次方 boolean c = true && false || true && true; System.out.println(a+" "+aa+" "+b); if (c) System.out.println(true); else System.out.println(false); } } 

1.1.2

package ch1.ch1_1.pratice;

import edu.princeton.cs.algs4.StdOut;

public class P1_1_2 {
	public static void main(String[] args) {
		double a = (1+2.236)/2;
		double  b = 1+2+3+4.0;
		boolean c= 4.1<=4;
		String d = 1+2+"3";
		
		System.out.println(a+" "+b+" "+d);
		if(c) StdOut.println(true);
		else StdOut.println(false);
	}
}

1.1.3

package ch1.ch1_1.pratice;

import java.util.Scanner;

import edu.princeton.cs.algs4.StdIn;

public class P1_1_3 {
	



	public static void main(String[] args) {
		int a = StdIn.readInt();//stdIn 中的输入是从控制台输入  
		int b = StdIn.readInt();//相当于int b = scanner.nextInt();
		int c = StdIn.readInt();
		if (a == b && a == c) {
			System.out.println("equal");
		} else {
			System.out.println("not equal");
		}
	}

}

1.1.5

package ch1.ch1_1.pratice;

import edu.princeton.cs.algs4.StdIn;
import edu.princeton.cs.algs4.StdOut;

public class P1_1_5 {
	public static void main(String[] args) {
		double x = StdIn.readDouble();
		if (x>0.0&&x<1.0) StdOut.println("true");
		else StdOut.println("false");
	}
}

1.1.6

package ch1.ch1_1.pratice;

import edu.princeton.cs.algs4.StdOut;

public class P1_1_6 {
	public static void main(String[] args) {
		int f = 0;
		int g = 1;
		for(int i = 0;i<= 15;i++){
			StdOut.println(f);
			f = f+g;
			g = f-g;
		}
	}
}
/*
 * 0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610

 * */
 

1.1.7

package ch1.ch1_1.pratice;

import edu.princeton.cs.algs4.StdOut;

public class P1_1_7a {
	public static void main(String[] args) {
		double t = 9.0;
		while (Math.abs(t - 9.0 / t) > .001) {
			t = (9.0 / t + t) / 2.0;
		}
		StdOut.printf("%.5f\n", t); 
	}
}
/*
 * 3.00009
 * */

package ch1.ch1_1.pratice; public class P1_1_7b { public static void main(String[] args) { int sum = 0; for (int i = 1; i < 1000; i++) for (int j = 0; j < i; j++) sum++; System.out.println(sum);//499500 } }

1.1.7c

package ch1.ch1_1.pratice;

public class P1_1_7c {
	public static void main(String[] args) {
		int sum  = 0;
		for(int i = 1;i<1000;i*=2){
			for(int j = 0;j<1000;j++)
				{sum++;}
		}
		
		System.out.println(sum);//10000

	}
}

1.1.8

package ch1.ch1_1.pratice;

public class P1_1_8 {
	public static void main(String[] args) {
		System.out.println('a');//a
		System.out.println('b'+'c');//98+99
		System.out.println((char)('a'+4));//e
	}
}