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greedy_algorithm.go
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/
greedy_algorithm.go
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package grokking_algorithms
type (
Station string
State string
States map[State]struct{}
Stations map[Station]States
)
func (s States) copy() States {
statesCopy := make(States)
for state := range s {
statesCopy[state] = struct{}{}
}
return statesCopy
}
func (s States) intersection(states States) States {
statesCopy := make(States)
for state := range states {
if s.contains(state) {
statesCopy[state] = struct{}{}
}
}
return statesCopy
}
func (s States) contains(search State) bool {
for state := range s {
if state == search {
return true
}
}
return false
}
func (s States) remove(states States) States {
statesCopy := make(States)
for state := range s {
if !states.contains(state) {
statesCopy[state] = struct{}{}
}
}
return statesCopy
}
func GreedyStations(stations Stations, statesNeeded States) []Station {
result := make([]Station, 0, len(stations))
needed := statesNeeded.copy()
for len(needed) > 0 {
var bestStation Station
bestStationCoverage := make(map[State]struct{})
for station, states := range stations {
coveredStates := states.intersection(needed)
if len(coveredStates) > len(bestStationCoverage) {
bestStationCoverage = coveredStates
bestStation = station
}
}
needed = needed.remove(bestStationCoverage)
result = append(result, bestStation)
}
return result
}