题解 | #大整数相乘#

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String a = in.next();
        String b = in.next();
        int[] res = new int[a.length() + b.length()];
	    // 先进行累乘 与 相加
        for (int i = a.length() - 1; i > -1; i--) {
            int start = a.length() - i - 1;
            for (int j = b.length() - 1; j > -1; j--) {
                int k = (a.charAt(i) - '0') * (b.charAt(j) - '0');
                res[start++] += k;
            }
        }
	    // 再对数据进行进位
        StringBuilder sb = new StringBuilder();
        int p = 0;
        for (int i = 0; i < res.length; i++) {
            res[i] += p;
            p = res[i] / 10;
            res[i] %= 10;
            sb.append(res[i]);
        }
	    // 格式化数据
        String tmp = sb.reverse().toString();
        for (int i = 0; i < tmp.length(); i++) {
            if (tmp.charAt(i) != '0') {
                System.out.println(tmp.substring(i));
                break;
            }
        }
    }
}