题目要求大概:
输入a,b两个大数,长度100以内,默认a>=b;不考虑其他情况;
例如:输入 1000000000000001
1
输出 1000000000000000
import java.util.Scanner; public class Main { public static String func(String a,String b) { int[] aa = new int[a.length()]; int[] bb = new int[b.length()]; for (int i = 0; i < a.length(); i++) { aa[i] = Integer.valueOf(String.valueOf(a.charat(i))); } for (int i = 0; i < b.length(); i++) { bb[i] = Integer.valueOf(String.valueOf(b.charat(i))); } int index = b.length(); for (int i = a.length() - 1; i >= 0; i--) { if (index >= 1) { if (aa[i] >= bb[index - 1]) { aa[i] = aa[i] - bb[index - 1]; } else { int temp = 1; while (aa[i - temp] == 0) { aa[i - temp] = 9; temp++; } aa[i - temp]--; aa[i] = aa[i] + 10 - bb[index - 1]; } index--; } } int start = a.length()-1; for (int i = 0; i < a.length(); i++) { if (aa[i] != 0) { start = i; break; } } String result = ""; for (int i = start; i < a.length(); i++) { result += aa[i]; } return result; } public static void main(String[] args) { String a = ""; String b = ""; Scanner cin = new Scanner(system.in); while (cin.hasNext()) { if (a == "") { a = cin.nextLine(); } else { b = cin.nextLine(); System.out.println(func(a,b)); a = ""; b = ""; } } } }