题解 | #字符串排序#

package main

import (
	"fmt"
	"os"
	"sort"
	"strings"
    "bufio"
)

// 插入排序
func insertSort(s string) string {
    size := len(s)

    // 先收集所有字符
    var letters []byte
    for i:=0; i<size; i++ {
        if ('A' <= s[i] && s[i] <= 'Z') || ('a' <= s[i] && s[i] <= 'z') {
            letters = append(letters, s[i])
        }
    }

    // 对所有字符忽略大小写稳定排序
    sort.SliceStable(letters, func(i, j int) bool {
        return strings.ToLower(string(letters[i])) < strings.ToLower(string(letters[j]))
    })

    sb := make([]byte, size)
    idx := 0
    for i:=0; i<size; i++ {
        if ('A' <= s[i] && s[i] <= 'Z') || ('a' <= s[i] && s[i] <= 'z') {
            sb[i] = letters[idx]
            idx++
        } else {
            sb[i] = s[i]
        }
    }

    return string(sb)
}

func main() {
    var s string

    inputReader := bufio.NewReader(os.Stdin)
    line, _, _ := inputReader.ReadLine()

    s = string(line)

    fmt.Println(insertSort(s))
}

// 本题输入一行字符串，所以采用 inputReader.ReadLine()