70 lines
2.0 KiB
Go
70 lines
2.0 KiB
Go
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package interpol
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/* ---------------------------------------------------------------- *
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* IMPORTS
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* ---------------------------------------------------------------- */
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import (
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"fmt"
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"math"
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"ads/internal/core/logging"
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"ads/internal/core/metrics"
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)
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/* ---------------------------------------------------------------- *
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* GLOBAL VARIABLES/CONSTANTS
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* ---------------------------------------------------------------- */
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//
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/* ---------------------------------------------------------------- *
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* ALGORITHM interpolation
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* ---------------------------------------------------------------- */
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/*
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Inputs: L = Liste von Zahlen, x = Zahl.
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Annahme: L sei aufsteigend sortiert.
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Outputs: Position von x in L, sonst −1 wenn x nicht in L.
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*/
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func InterpolationSearch(L []int, x int, u int, v int) int {
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if len(L) == 0 {
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logging.LogDebug(fmt.Sprintf("Liste L leer, also x nicht in L"))
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return -1
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} else if !(L[u] <= x && x <= L[v]) {
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logging.LogDebug(fmt.Sprintf("x liegt außerhalb der Grenzen von L"))
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return -1
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}
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metrics.AddTimeCost()
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p := getSuchposition(L, x, u, v)
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logging.LogDebug(fmt.Sprintf("Interpolante von x in (u, v)=(%[1]v, %[2]v) ist p = %[3]v.", u, v, p))
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if L[p] == x {
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logging.LogDebug(fmt.Sprintf("x in Position p gefunden"))
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return p
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} else if x < L[p] {
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logging.LogDebug(fmt.Sprintf("Suche in linker Hälfte fortsetzen."))
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return InterpolationSearch(L, x, u, p-1)
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} else { // } else if x > L[p] {
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logging.LogDebug(fmt.Sprintf("Suche in rechter Hälfte fortsetzen."))
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return InterpolationSearch(L, x, p+1, v)
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}
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}
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/* ---------------------------------------------------------------- *
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* ALGORITHM interpolation
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* ---------------------------------------------------------------- */
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/*
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Inputs: L = Liste von Zahlen, x = Zahl, [u, v] = Suchinterval.
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Outputs: Interpolierte Position, um Suchinterval ausgeglichen aufzuteilen.
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*/
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func getSuchposition(L []int, x int, u int, v int) int {
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metrics.AddTimeCost()
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r := float64(x-L[u]) / float64(L[v]-L[u])
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p := int(math.Floor(float64(u) + r*float64(v-u)))
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return p
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}
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