Java usage in ACM

The main application of Java in ACM is the big data class [personal opinion ]. Make a summary and use it as a template.

The default class name is main.

Input:

Declare an input object CIN; CIN = new expect (system. In );

Enter an int value: int A = cin. nextint ();

Enter a large number: bigdecimal A = cin. nextbigdecimal ();

End of EOF: While (CIN. hasnext ()){...}

Output:

Output STR [any type]: system. Out. println (STR); [with line breaks] system. Out. Print (STR); [without line breaks]

System. Out. println ("str"); [Output string STR]

Assignment:Biginteger A = new biginteger (string. valueof (12 ));

Special Functions for large numbers:

Equal judgment: C. compareto (bigdecimal. Zero) = 0 [c =]

If the value is greater than: C. compareto (bigdecimal. Zero)> 0 [C is greater than 0]

Judge less than: C. compareto (bigdecimal. Zero) <0 [C less than 0]

Modify the format: C. striptrailingzeros (). toplainstring (); [C. Remove 0 at the end and convert it to another string]

String functions:

Str. startwith ("0"). [start with 0] Str. endwith ("0") [end with 0]

Str. substring (int x, int y) [substring of STR from X to Y] Str. substring (int x) [substring of STR from X to the end]

Biginteger functions:

Construction: Public biginteger (string Str) [convert string type data to a large integer]

Construction: Public biginteger POW (bigdecimal B) [power B]

Add: Public biginteger add (biginteger B) [add B]

Minus: Public biginteger subtract (biginteger B) [minus B]

Multiply: Public biginteger multiply (biginteger B) [multiply by B]

Except: Public biginteger divided (biginteger B) [Except B]

Maximum Value: Public biginteger max (biginteger A) [returns the maximum value]

Minimum value: Public biginteger min (biginteger A) [returns the minimum value]

Except: Public biginteger [] dividedandremainder (biginteger B) [in addition to B, the first digit of the array is the quotient, and the second digit is the remainder]

Bigdecimal functions:

Structure: Public bigdecimal (string Str) [convert string type data to high precision Data]

Public bigdecimal (INT Str) [convert int type data to a big integer]

Public bigdecimal (double Str) [convert data of the double type to a big integer]

Power: Public bigdecimal POW (bigdecimal B) [power B]

Add: Public bigdecimal add (bigdecimal B) [add B]

Minus: Public bigdecimal subtract (bigdecimal B) [minus B]

Multiply: Public bigdecimal multiply (bigdecimal B) [multiply by B]

Except: Public biginteger divided (biginteger B) [Except B]

Example:

A + B. Output the simplest result

Import Java. math. bigdecimal; // import a high-precision package into Java. util. *; // The package where the input and output are located. [almost all the Code must be included.] public class main {public static void main (string [] ARGs) {CIN = new partition (system. in); bigdecimal A, B, C; while (CIN. hasnext () {A = cin. nextbigdecimal (); B = cin. nextbigdecimal (); C =. add (B); If (C. compareto (bigdecimal. zero) = 0) {system. out. println ("0"); continue;} string STR = C. striptrailingzeros (). toplainstring (); If (Str. endswith (". ") STR = Str. substring (0, str. length ()-1); system. out. println (STR );}}}

A's factorial:

 import java.util.*;import java.math.*;public class Main{    public static void main(String args[])    {        int m,i;        Scanner in = new Scanner(System.in);        m=in.nextInt();        BigInteger sum = new BigInteger(String.valueOf(m));        for(i=m-1;i>0;i--)        {            BigInteger x =new BigInteger(String.valueOf(i));            sum=sum.multiply(x);        }        System.out.println(sum);    }}