108 lines
2.6 KiB
Go
108 lines
2.6 KiB
Go
package next_greater_element
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/* ---------------------------------------------------------------- *
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* IMPORTS
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* ---------------------------------------------------------------- */
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import (
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"ads/internal/core/logging"
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"ads/internal/core/metrics"
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"ads/internal/data_structures/stacks"
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)
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/* ---------------------------------------------------------------- *
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* GLOBAL VARIABLES/CONSTANTS
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* ---------------------------------------------------------------- */
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var _output_list [][2]int
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/* ---------------------------------------------------------------- *
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* ALGORITHM next greater element
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* ---------------------------------------------------------------- */
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/*
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Inputs: L = Liste von Zahlen, x = Zahl.
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Outputs: Liste von Paaren von Elementen und ihrem nächsten größeren Element
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*/
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func NextGreaterElement(L []int) [][2]int {
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clearOutput()
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if len(L) == 0 {
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return output()
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}
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S := stacks.CREATE()
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for i := 0; i < len(L); i++ {
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logging.Debug("Lies Element L[%v] ein", i)
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nextElement := L[i]
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logging.Debug("Stack S | %v", S)
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if !S.EMPTY() {
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logging.Debug("Entferne alle top Elemente vom Stack bis >= nextElement")
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element := S.TOP()
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S.POP()
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metrics.AddTimeCost()
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/*
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Entferne kleinere Elemente vom Stack
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Aktuelles Element ist jeweils größerer rechter Partner
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*/
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for element < nextElement {
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logging.Debug("Stack S | %v", S)
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addToOutput(element, nextElement)
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if S.EMPTY() {
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break
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}
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element = S.TOP()
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S.POP()
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metrics.AddTimeCost()
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}
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// lege letztes Element zurück
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if element > nextElement {
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logging.Debug("Element >= nextElement zurücklegen")
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S.PUSH(element)
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metrics.AddTimeCost()
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}
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logging.Debug("Stack S | %v", S)
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}
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S.PUSH(nextElement)
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metrics.AddTimeCost()
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logging.Debug("L[%v] auf Stack legen", i)
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logging.Debug("Stack S | %v", S)
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}
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// was übrig bleibt hat kein größeres Element
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logging.Debug("Alles übrige auf Stack hat kein nächstes größeres Element")
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for !S.EMPTY() {
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metrics.AddTimeCost()
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logging.Debug("Stack S | %v", S)
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element := S.TOP()
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S.POP()
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addToOutput(element, -1)
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}
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logging.Debug("Stack S | %v", S)
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return output()
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}
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/* ---------------------------------------------------------------- *
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* AUXILIARY METHODS
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* ---------------------------------------------------------------- */
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func clearOutput() {
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_output_list = [][2]int{}
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}
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func addToOutput(m int, n int) {
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_output_list = append(_output_list, [2]int{m, n})
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}
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func output() [][2]int {
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var output = make([][2]int, len(_output_list))
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copy(output, _output_list)
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clearOutput()
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return output
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}
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