题解 | #合法IP#

package main

import (
    "fmt"
    "strings"
    "strconv"
)

func isValidIP(ip string) bool {
    ipSegments := strings.Split(ip, ".")
    if len(ipSegments) != 4 {
        return false
    }
    for _, ipSegment := range ipSegments {
        if len(ipSegment) > 1 && (ipSegment[0] == '0' || ipSegment[0] == '+') {
            return false
        }
        ipSegmentNumber, err := strconv.Atoi(ipSegment)
        if err != nil {
            return false
        }
        if ipSegmentNumber < 0 || ipSegmentNumber > 255 {
            return false
        }
    }

    return true
}

func main() {
    var ip string
    fmt.Scan(&ip)
    if !isValidIP(ip) {
        fmt.Println("NO")
    } else {
        fmt.Println("YES")
    }
}

// 本题输入一行字符串，所以采用：fmt.Scan(&ip)