func MinValue(state adversarial.State, alpha float64, beta float64) (adversarial.Action, float64) {
if state.Terminal() {
return nil, state.Utility()
}
var min *adversarial.Successor
var minvalue = math.Inf(1)
successors := state.Successors()
for i, successor := range successors {
_, value := MaxValue(successor.State, alpha, beta)
if min == nil || minvalue > value {
min = &successors[i] // can't do &successor #wtfgo
minvalue = value
}
if minvalue <= alpha {
debug(fmt.Sprintf("MinValue %v pruning at %v => (%v, %f)", state, successor, min.Action, minvalue))
return min.Action, minvalue
}
beta = math.Min(beta, minvalue)
}
if min == nil {
panic(fmt.Sprintf("Non-terminal state has zero successors %v", state))
}
debug(fmt.Sprintf("MinValue %v => (%v, %f", state, min.Action, minvalue))
return min.Action, minvalue
}
func MaxValue(state adversarial.State, alpha float64, beta float64) (adversarial.Action, float64) {
if state.Terminal() {
return nil, state.Utility()
}
var max *adversarial.Successor
var maxvalue = math.Inf(-1)
successors := state.Successors()
for i, successor := range successors {
_, value := MinValue(successor.State, alpha, beta)
if max == nil || maxvalue < value {
max = &successors[i]
maxvalue = value
}
if maxvalue >= beta {
debug(fmt.Sprintf("MaxValue %v pruning at %v => (%v, %f)", state, successor, max.Action, maxvalue))
return max.Action, maxvalue
}
alpha = math.Max(alpha, maxvalue)
}
if max == nil {
panic(fmt.Sprintf("Non-terminal state has zero successors %v", state))
}
debug(fmt.Sprintf("MaxValue %v => (%v, %f)", state, max.Action, maxvalue))
return max.Action, maxvalue
}