对地图进行排序 [string][]struct{}

Question

我想按成本对这张地图进行排序type Graph struct {    vertice string    cost    float64}var graph map[string][]Graph按照从低到高的顺序

Answer 1

如果目标是graph按成本对每个切片进行排序，则只需实现sort.Interfaceon []Graph，然后使用 for 循环遍历值。

type ByCost []Graph

func (gs *ByCost) Len() int { return len(gs) }

func (gs *ByCost) Less(i, j int) bool { return gs[i].cost < gs[j].cost }

func (gs *ByCost) Swap(i, j int) { gs[i], gs[j] = gs[j], gs[i] }

for _, v := range graph {

    sort.Sort(ByCost(v))

如果您尝试按照中的成本总和排序的顺序遍历地图[]Graph，那将变得不那么干净。

type GraphKeyPairs struct {

    key string

    value []Graph

}

// Build a slice to store our map values

sortedGraph := make([]GraphKeyPairs, 0, len(graph))

for k,v := range graph {

    // O(n)

    gkp := GraphKeyPairs{key: k, value: v}

    sortedGraph = append(sortedGraph, gkp)

}

type BySummedCost []GraphKeyPairs

func (gkp *BySummedCost) Len() int { return len(gkp) }

func (gkp *BySummedCost) Swap(i, j int) { gkp[i], gkp[j] = gkp[j], gkp[i] }

func (gkp *BySummedCost) Less(i, j int) bool {

    // O(2n)

    iCost, jCost := 0, 0

    for _, v := range gkp[i].value {

        iCost += v.cost

    }

    for _, v := range gkp[j].value {

        jCost += v.cost

    }

    return iCost < jCost

}

sort.Sort(BySummedCost(sortedGraph))