java在acm中常用基础技巧方法

如果学到了新的技巧，本博客会更新~

input

input-std

@Frosero
import java.util.*;

public class Main {
    static String a;
    static int c;
    static Scanner cin = new Scanner(System.in);
    public static void main(String[] args) {
        while(cin.hasNext()){     // while(scanf("%d",&a)!=EOF)
            a = cin.next();       // input : %d
            c = cin.nextInt();    // input : %s
        }
    }

}

input-file

@Frosero
import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.*;


public class Main {
    static int x,y;
    public Main() throws FileNotFoundException{
        Scanner cin = new Scanner(new File("test.in"));
        PrintWriter cout = new PrintWriter(new File("test.out"));
        x = cin.nextInt();
        y = cin.nextInt();
        cout.println(x + y);
        cout.close();
    }
    public static void main(String[] args) throws FileNotFoundException {
        new Main();
    }
}

output

@Frosero
public class Main {
    public static void main(String[] args) {
        System.out.print("hello world !");      //printf("hello world !");
        System.out.println("hello world !");    //printf("hello world !\n");
    }
}

BigInteger

    需要特别说明的就是BigInteger需要由String转化过来。如果是整数，直接toString就好了。

@Frosero
import java.math.BigInteger;


public class Main {
    static BigInteger a = new BigInteger("9876543210");
    static BigInteger b = new BigInteger("27");
    static BigInteger m = new BigInteger("1000000007");
    public static void main(String[] args) {
        System.out.println(a.add(b));           // +

        System.out.println(a.subtract(b));      // -

        System.out.println(a.multiply(b));      // *

        System.out.println(a.divide(b));        // /

        System.out.println(a.mod(b));           // %

        System.out.println(a.compareTo(b));     // a > b : 1 ; a < b : -1 ; a == b : 0 ;

        System.out.println(a.equals(b));        // a == b : true ;

        System.out.println(a.isProbablePrime(1));   // probable : true ; 

        System.out.println(a.gcd(b));           // gcd

        System.out.println(a.modPow(b, m));     // pow + %

        // max min or xor and  .......
    }
}