LeetCode: Minimize Max Distance to Gas Station

// https://code.dennyzhang.com/minimize-max-distance-to-gas-station
// Basic Ideas: binarysearch
//  Mononotic function: the bigger K is, the smaller D would be
// Complexity: Time O(n*log(m)), Space O(1)
import "sort"
func isPossible(stations []int, K int, D float64) bool {
    count := 0
    for i:=0; i+1<len(stations); i++ {
        dis := float64(stations[i+1]-stations[i])
        if dis <= D {
            continue
        }
        add := int(dis/D)
        count += add
        if float64(add)*D > dis {
            count++
        }
    }
    return count <= K
}

func minmaxGasDist(stations []int, K int) float64 {
    sort.Ints(stations)
    left, right := float64(0), float64(stations[len(stations)-1]-stations[0])
    // always can find
    for right-left > 0.000006 {
        mid := (right-left)/2 + left
        // F, F, F, T, T, T
        if isPossible(stations, K, mid) {
            // left half
            right = mid
        } else {
            // right half
            left = mid
        }
    }
    return left
}