Java之數組計算大數相乘

Java之數組計算大數相乘

1. public class ArrayMulti {
2. public static void main(String[] args) throws Exception {
3. // TODO Auto-generated method stub
4. int[] date = new int[100000];
5. date[1] = 1;
6. int weishu = 1; // 求出來的值的位數
7. System.out.println("------用數組解決大數問題---------");
8. System.out.println("求n！的值");
9. System.out.print("n=");
10. Scanner cin = new Scanner(System.in);
11. int n = cin.nextInt();
12. for (int i = 1; i <= n; i++) {
13. for (int j = 1; j <= weishu; j++) {
14. date[j] = date[j] * i;
15. }
16. // 確保除最高位外的每位不大於9
17. for (int j = 1; j < weishu; j++) {
18. if (date[j] >= 10) {
19. date[j + 1] += date[j] / 10;
20. date[j] = date[j] % 10;
21. }
22. }
23. // 確保最高位不大於9
24. while (date[weishu] >= 10) {
25. weishu++;
26. date[weishu] += date[weishu - 1] / 10;
27. date[weishu - 1] = date[weishu - 1] % 10;
28. }
29. }
31. System.out.print(n + "!= ");
32. for (int k = weishu; k >= 1; k--) {
33. System.out.print(date[k]);
34. }
35. System.out.println("");
36. }
37. }