杭电ACM1000,1001,1002 java解答

1000 .
Problem Description
Calculate A + B.

Input
Each line will contain two integers A and B. Process to end of file.

Output
For each case, output A + B in one line.

注意Process to end of file.

import java.util.Scanner;public class Main {    public static void main(String args[]){        int a,b;        Scanner s=new Scanner(System.in);        while(s.hasNextInt()){            a=s.nextInt();            b=s.nextInt();            System.out.println((a+b));        }    }}

1001 .
Problem Description
Hey, welcome to HDOJ(Hangzhou Dianzi University Online Judge).

In this problem, your task is to calculate SUM(n) = 1 + 2 + 3 + … + n.

Input
The input will consist of a series of integers n, one integer per line.

Output
For each case, output SUM(n) in one line, followed by a blank line. You may assume the result will be in the range of 32-bit signed integer.

注意计算n*(n-1)会产生溢出。

import java.util.Scanner;public class Main {    public static void main(String args[]){        Scanner s=new Scanner(System.in);        while(s.hasNextInt()){            int n=s.nextInt();            if((n<<31)>>31==0){                int sum=n/2;                sum=sum*(n+1);                System.out.println(sum);                System.out.println();            }            else{                int sum=(n+1)/2;                sum=sum*n;                System.out.println(sum);                System.out.println();            }        }    }}

1002.

Problem Description
I have a very simple problem for you. Given two integers A and B, your job is to calculate the Sum of A + B.

Input
The first line of the input contains an integer T(1<=T<=20) which means the number of test cases. Then T lines follow, each line consists of two positive integers, A and B. Notice that the integers are very large, that means you should not process them by using 32-bit integer. You may assume the length of each integer will not exceed 1000.

Output
For each test case, you should output two lines. The first line is “Case #:”, # means the number of the test case. The second line is the an equation “A + B = Sum”, Sum means the result of A + B. Note there are some spaces int the equation. Output a blank line between two test cases.

注意最后一个输出之后不需要再换行了。

import java.math.BigInteger;import java.util.Scanner;public class Main {    public static void main(String args[]){        Scanner s=new Scanner(System.in);        int T=s.nextInt();        for(int i=0;i<T;i++){            BigInteger a=s.nextBigInteger();            BigInteger b=s.nextBigInteger();            BigInteger c=a.add(b);            System.out.println("Case "+(i+1)+":");            System.out.println(a.toString()+" + "+b.toString()+" = "+c.toString());            if(i!=T-1)                  System.out.println();        }    }}