题解 | #大数加法#

using System;
using System.Collections.Generic;
using System.Text;

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 string solve (string s, string t) {
        // write code here
        if (t.Length == 0) return s;
        if (s.Length == 0) return t;
        if (s.Length < t.Length) {
            string temp = "";
            temp = s;
            s = t;
            t = temp;
        }
        StringBuilder sb = new StringBuilder();
        int carry = 0;
        for (int i = s.Length - 1; i >= 0 ; i--) {
            int temp = s[i] - '0' + carry;
            int j = i - s.Length + t.Length;
            if (j >= 0)
                temp = t[j] - '0' + temp;
            carry = temp / 10;
            temp %= 10;
            sb.Append((char)(temp + '0'));
        }
        if (carry == 1) sb.Append('1');
        StringBuilder res = new StringBuilder();
        for (int i = sb.Length - 1; i >= 0 ; i--) {
            res.Append(sb[i]);
        }
        return res.ToString();
    }
}