题解 | #大数加法#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 计算两个数之和
     * @param s string字符串 表示第一个整数
     * @param t string字符串 表示第二个整数
     * @return string字符串
     */
    public static String solve (String s, String t) {
        // write code here
        StringBuilder sbs = new StringBuilder(s);
        StringBuilder sbt = new StringBuilder(t);

        StringBuilder res = new StringBuilder();
        int carry = 0;
        while (sbs.length() != 0 || sbt.length() != 0) {
            int a = 0;
            int b = 0;
            if (sbs.length() != 0) {
                //字符变整形-‘0’
                a = sbs.charAt(sbs.length() - 1) - '0';
                sbs.deleteCharAt(sbs.length() - 1);
            }

            if (sbt.length() != 0) {
                b = sbt.charAt(sbt.length() - 1) - '0';
                sbt.deleteCharAt(sbt.length() - 1);
            }
            int sum = a + b + carry;
            res.append(sum % 10);
            carry = (a + b + carry) / 10;
        }
        if (carry > 0) {
            res.append(1);
        }
        String r = res.reverse().toString();
        return r;
    }
}