Java面向对象2（G~J）

G    织女的红线（SDUT 2240）

import java.util.Scanner;
import java.text.DecimalFormat;

class Sum {
	double x1, y1, x2, y2;

	Sum(double n1, double m1, double n2, double m2) {
		x1 = n1;
		x2 = n2;
		y1 = m1;
		y2 = m2;
	}

	double getAns() {
		double ans = 0;
		ans = (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
		ans = Math.sqrt(ans);
		return ans;
	}
}

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		DecimalFormat df = new DecimalFormat(".00");
		int t, r;
		double ans = 0;
		double x[] = new double[200];
		double y[] = new double[200];
		t = sc.nextInt();
		r = sc.nextInt();
		for (int i = 1; i <= t; i++) {
			x[i] = sc.nextDouble();
			y[i] = sc.nextDouble();
		}
		x[t + 1] = x[1];
		y[t + 1] = y[1];
		Sum p;
		for (int i = 1; i <= t; i++) {
			p = new Sum(x[i], y[i], x[i + 1], y[i + 1]);
			ans += p.getAns();
		}
		ans += 2 * r * 3.1415926;
		System.out.println(df.format(ans));
	}
}

H     分数加减法（SDUT 2253）

import java.util.Scanner;
import java.text.DecimalFormat;

class Sum {
	int x1, y1, x2, y2;
	char str;

	Sum(int n1, int m1, int n2, int m2, char op) {
		x1 = n1;
		x2 = n2;
		y1 = m1;
		y2 = m2;
		str = op;
	}

	int getGcd(int a, int b) {
		int n = a, m = b;
		while (m > 0) {
			int x = n;
			n = m;
			m = x % m;
		}
		return n;
	}

	void getAns() {
		int x = getGcd(y1, y2);
		int a, b, c, d, ans1, ans2;
		a = x1;
		b = y1;
		c = x2;
		d = y2;
		int lcm = b * d / x;
		a = a * d / x;
		c = c * b / x;
		if (str == '+')
			ans1 = a + c;
		else
			ans1 = a - c;
		ans2 = lcm;
		if (ans1 < 0)
			x = -ans1;
		else
			x = ans1;
		x = getGcd(x, ans2);
		if (ans1 % x == 0 && ans2 % x == 0) {
			ans1 /= x;
			ans2 /= x;
		}
		if (ans1 == 0 && ans1 != ans2 || ans2 == 1)
			System.out.println(ans1);
		else if (ans1 == ans2)
			System.out.println(1);
		else
			System.out.println(ans1 + "/" + ans2);
	}
}

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		// DecimalFormat df = new DecimalFormat(".00");
		Sum p;
		String s;
		char op;
		while (sc.hasNext()) {
			s = sc.next();
			// System.out.println(s);
			int x1 = s.charAt(0) - '0';
			int y1 = s.charAt(2) - '0';
			op = s.charAt(3);
			int x2 = s.charAt(4) - '0';
			int y2 = s.charAt(6) - '0';
			// System.out.println(x1 + " " + y1 + " " + x2 + " " + y2 + " " + op);
			p = new Sum(x1, y1, x2, y2, op);
			p.getAns();
		}
	}
}

高中数学？（SDUT 2400）

import java.util.*;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int t = sc.nextInt();
		for (int i = 0; i < t; i++) {
			int n = sc.nextInt();
			Sum p = new Sum(n);
			int ans = p.getAns(n);
			System.out.println(ans);
		}
		sc.close();
	}
}

class Sum {
	int a[] = new int[55];
	int n;

	public Sum(int n) {
		a[1] = 0;
		a[2] = 1;
		for (int i = 3; i <= 50; i++) {
			a[i] = 4 * a[i - 1] - 5 * a[i - 2];
		}
		this.n = n;
	}

	public int getAns(int n) {
		return a[n];
	}
}

最大矩形面积（SDUT 2401）

import java.lang.reflect.Array;
import java.util.*;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int t = sc.nextInt();
		int n,l,w;
		node s[] = new node[2000];
		for (int i = 0; i < t; i++) {
			l = sc.nextInt();
			w = sc.nextInt();
			n = sc.nextInt();
			for(int j = 0; j < n; j ++)
			{
				s[j] = new node();
				s[j].x = sc.nextInt();
				s[j].y = sc.nextInt();
			}
			//Arrays.sort(s,0,n,new cmp());
			Sum p = new Sum(l,w,n,s);
			if(n == 0)
				System.out.println(l * w);
			else
				System.out.println(p.getAns());
		}
		sc.close();
	}
}

class node
{
	int x;
	int y;
}
class cmp implements Comparator<node>
{
	public int compare(node a, node b)
	{
		if(a.x - b.x != 0) return a.x - b.x;
		else return a.y - b.y;
	}
}
class cmp1 implements Comparator<node>
{
	public int compare(node a, node b)
	{
		if(a.y - b.y != 0) return a.y - b.y;
		else return a.x - b.x;
	}
}
class Sum {
	int l,w,n;
	node s[] = new node[2000];
	Sum(int l, int w, int n, node s[])
	{
		this.l = l;
		this.w = w;
		this.n = n;
		this.s = s;
	}
	int max(int a, int b)
	{
		if(a >= b) return a;
		else return b;
	}
	int min(int a, int b)
	{
		if(a >= b) return b;
		else return a;
	}
	int getAns1()
	{
			Arrays.sort(s,0,n,new cmp1());
		 	int i,j,ans1;
		    ans1 = 0;
		    for (i = 0; i < n; ++i)
		    {
		        int L = 0, R = l;
		        for (j = i + 1; j < n; ++j)
		        {
		            if (s[i].y != s[j].y)
		            {
		                ans1 = max(ans1,(s[j].y - s[i].y)*(R - L));
		                if (s[j].x > s[i].x)  R = min(R,s[j].x);
		                else   L = max(L,s[j].x);
		            }
		        }
		    }
		    return ans1;
	}
	int getAns2()
	{
		Arrays.sort(s,0,n,new cmp());
		  int i,j,ans2;
		    ans2 = 0;
		    for (i = 0; i < n; ++i)
		    {
		        int top = w, down = 0;
		        for (j = i + 1; j < n; ++j)
		        {
		            if (s[i].x != s[j].x)
		            {
		                ans2 = max(ans2,(s[j].x - s[i].x)*(top - down));
		                if (s[j].y > s[i].y)  top =  min(top,s[j].y);
		                else  down = max(down,s[j].y);
		            }
		        }
		    }
		    return ans2;
	}
	int getAns()
	{
		int ans,ans1,ans2;
		ans1 = getAns1();
		ans2 = getAns2();
		ans = max(ans1,ans2);
		return ans;
	}
}