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HDU-4927 Series 1
http://acm.hdu.edu.cn/showproblem.php?pid=4927
同学用java写的大整数相减
Series 1
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 262144/262144 K (Java/Others) Total Submission(s): 295 Accepted Submission(s): 100
Problem Description
Let A be an integral series {A1, A2, . . . , An}.
The zero-order series of A is A itself.
The first-order series of A is {B1, B2, . . . , Bn-1},where Bi = Ai+1 - Ai.
The ith-order series of A is the first-order series of its (i - 1)th-order series (2<=i<=n - 1).
Obviously, the (n - 1)th-order series of A is a single integer. Given A, figure out that integer.
The zero-order series of A is A itself.
The first-order series of A is {B1, B2, . . . , Bn-1},where Bi = Ai+1 - Ai.
The ith-order series of A is the first-order series of its (i - 1)th-order series (2<=i<=n - 1).
Obviously, the (n - 1)th-order series of A is a single integer. Given A, figure out that integer.
Input
The input consists of several test cases. The first line of input gives the number of test cases T (T<=10).
For each test case: The first line contains a single integer n(1<=n<=3000), which denotes the length of series A. The second line consists of n integers, describing A1, A2, . . . , An. (0<=Ai<=105)
For each test case: The first line contains a single integer n(1<=n<=3000), which denotes the length of series A. The second line consists of n integers, describing A1, A2, . . . , An. (0<=Ai<=105)
Output
For each test case, output the required integer in a line.
Sample Input
2
3
1 2 3
4
1 5 7 2
Sample Output
0
-5
import java.math.BigInteger;import java.util.*;import java.io.*;public class Main { public static void main(String args[]) { Scanner in = new Scanner(System.in); int t = in.nextInt(); int a[] = new int[3005]; for (int cas = 1; cas <= t; cas++) { int n = in.nextInt(); int i, j; for (i = 1; i <= n; ++i) { a[i] = in.nextInt(); } BigInteger ans = BigInteger.valueOf(a[n]); BigInteger x = BigInteger.valueOf(1); BigInteger flag = BigInteger.valueOf(-1); n = n -1; for(i=1,j=n; i<=n; i++,j--) { x = x.multiply(BigInteger.valueOf(j)).divide(BigInteger.valueOf(i)); x = x.multiply(flag); ans = ans.add(x.multiply(BigInteger.valueOf(a[j]))); } System.out.println(ans); } }}
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