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;
  }
}