54 lines
1.3 KiB
Go
54 lines
1.3 KiB
Go
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package binary
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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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"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 binary search
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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 BinarySearch(L []int, x int) int {
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if len(L) == 0 {
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logging.LogDebug(fmt.Sprintf("x nicht in L"))
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return -1
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}
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metrics.AddTimeCost()
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m := int(len(L) / 2)
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if L[m] == x {
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logging.LogDebug(fmt.Sprintf("x in Position m gefunden"))
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return m
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} else if x < L[m] {
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logging.LogDebug(fmt.Sprintf("Suche in linker Hälfte fortsetzen."))
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index := BinarySearch(L[:m], x)
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return index
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} else { // } else if x > L[m] {
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logging.LogDebug(fmt.Sprintf("Suche in rechter Hälfte fortsetzen."))
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index := BinarySearch(L[m+1:], x)
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if index >= 0 {
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index += (m + 1) // NOTE: muss Indexwert kompensieren
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}
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return index
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}
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}
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