题解 | #高精度整数加法#

package main

import (
    "fmt"
    "strconv"
)

func stringAdd(s1 string, s2 string) string {
    var s string

    var step int
    idx1, idx2 := len(s1)-1, len(s2)-1
    for idx1 >= 0 || idx2 >= 0 {
        var n1 int
        var n2 int
        if idx1 >= 0 {
            n1 = int(s1[idx1] - '0')
            idx1--
        }
        if idx2 >= 0 {
            n2 = int(s2[idx2] - '0')
            idx2--
        }

        sum := (n1 + n2 + step) % 10
        step = (n1 + n2 + step) / 10

        s = strconv.Itoa(sum) + s
    }

    if step == 1 {
        s = strconv.Itoa(step) + s
    }

    return s
}

func main() {
    var s1 string
    var s2 string

    fmt.Scan(&s1, &s2)

    fmt.Println(stringAdd(s1, s2))
}

// 本题输入两个字符串，所以采用：fmt.Scan(&s1, &s2)