题解 | #路灯#

golang解法 注意边界 求数组值与值间隔最大

package main

import (
    "fmt"
    "io"
    "sort"
)

func main() {
    var n, l int
    for {
        _, err := fmt.Scan(&n, &l)
        if err == io.EOF {
            break
        }
        dis := make([]int, 0)
        var pos int
        for n > 0 {
            n--
            fmt.Scan(&pos)
            dis = append(dis, pos)
        }
        sort.Ints(dis)

        maxv := 0
        for i := 1; i < len(dis); i++ {
            if dis[i] - dis[i-1] > maxv {
                maxv = dis[i] - dis[i-1]
            }
        }
        // 考虑最先和最后两个边界
        board := max(2*(l - dis[len(dis)-1]), 2 * dis[0])
        if maxv < board {
            maxv = board
        }

        fmt.Printf("%.2f\n", float64(maxv)/2)
    }
}

func max(a, b int) int {
    if a >= b {
        return a
    }
    return b
}