题目

Given an integer, return its base 7 string representation.

Example 1:

Input: 100
Output: "202"

Example 2:

Input: -7
Output: "-10"

Note: The input will be in range of [-1e7, 1e7].

解题思路

1. 首先判断输入是否为负数，如果为负数，输出字符串上添加“-”，并将num取成正数
2. 对正整数循环取余数，并将获得的余数放在原字符串前面
3. 拼接字符串获得结果

注意
需要判断正整数是否为0，如果为零则转换为“0”

代码

base7.go

package _504_Base7

import "strconv"

func ConvertToBase7(num int) string {
    var ret string
    if num < 0 {
        ret += "-"
        num = -num
    }

    var base7 string
    if 0 == num {
        base7 = "0"
    } else {
        for ;num > 0; {
            base7 = strconv.Itoa(num % 7) + base7
            num = num / 7
        }
    }

    ret += base7

    return ret
}

测试

base7_test.go

package _504_Base7

import "testing"

func TestConvertToBase7(t *testing.T) {
    var tests = []struct{
        input int
        output string
    } {
        {-7, "-10"},
        {101, "203"},
        {0, "0"},
    }

    for _, v := range tests {
        ret := ConvertToBase7(v.input)

        if ret == v.output {
            t.Logf("pass")
        } else {
            t.Errorf("fail, want %+v, get %+v\n", v.output, ret)
        }
    }
}