（Java）A+B Problem(高精)

男娘i 2022-10-30 14:24 10阅读 0赞

# A+B Problem(高精度) #

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## [原题题意][Link 1] ##

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### 思路 ###

由于要运算的数a和b的范围远远可以超出int的表示范围，所以需要进行加法的模拟运算，即从个位数开始相加，如果数字之和大于10，那么就要进1，直至最高位。

### Java代码 ###

import java.util.*;
    import java.io.*;
    
    public class Main {
    
        public static void main(String[] args) throws IOException {
            StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
            Scanner sc = new Scanner(System.in);
            PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
            
            
            String a = sc.next();
            String b = sc.next();
            char[] cha = a.toCharArray();
            char[] chb = b.toCharArray();
            int a_len = a.length()-1;
            int b_len = b.length()-1;
            
            int len = Math.max(a_len, b_len)+2;
            char[] ans = new char[len];
            int flag = 0;
            //System.out.println("LEN: "+len);
            while(a_len >= 0 && b_len >= 0) {
                //System.out.println("A+B");
                int tmp_a = (int)cha[a_len] - '0';
                int tmp_b = (int)chb[b_len] - '0';
                int num = -1;
                if(flag == 1) {
                    num = tmp_a + tmp_b + 1;
                    //char ch = Character.forDigit(num, 10);
                    ans[--len] = (char)('0'+(num%10));
                    flag = 0;
                }else {
                    num = tmp_a + tmp_b;
                    //System.out.println("TEST OK! "+num);
                    //char ch = Character.forDigit(num, 10);
                    ans[--len] = (char)('0'+(num%10));
                    flag = 0;
                }
                if(num >= 10) {
                    flag = 1;
                }
                a_len--;
                b_len--;
            }
            while(a_len >= 0) {
                //System.out.println("A");
                int tmp_a = (int)cha[a_len] - '0';
                int num = -1;
                if(flag == 1) {
                    num = tmp_a + 1;
                    //char ch = Character.forDigit(num, 10);
                    ans[--len] = (char)('0'+(num%10));
                    flag = 0;
                }else {
                    num = tmp_a;
                    //System.out.println("TEST OK! "+num);
                    //char ch = Character.forDigit(num, 10);
                    ans[--len] = (char)('0'+(num%10));
                    flag = 0;
                }
                if(num >= 10) {
                    flag = 1;
                }
                a_len--;
            }
            while(b_len >= 0) {
                //System.out.println("B");
                int tmp_b = (int)chb[b_len] - '0';
                int num = -1;
                if(flag == 1) {
                    num = tmp_b + 1;
                    //char ch = Character.forDigit(num, 10);
                    ans[--len] = (char)('0'+(num%10));
                    flag = 0;
                }else {
                    num = tmp_b;
                    //System.out.println("TEST OK! "+num);
                    //char ch = Character.forDigit(num, 10);
                    ans[--len] = (char)('0'+(num%10));
                    flag = 0;
                }
                if(num >= 10) {
                    flag = 1;
                }
                b_len--;
            }
            if(flag == 1) {
                ans[--len] = '1';
            }
            for(int i = len; i < ans.length; i++) {
                System.out.print(ans[i]);
            }
            
            
        }
    }

[Link 1]: https://www.luogu.com.cn/problem/P1601