Ich hatte das gleiche Problem bei der Analyse der Ausführung dieses Backtrack-Algorithmus bei GeeksForGeeks. Sehen Sie selbst, wie das ausgeführt wird. Manchmal wirklich Druckwerte helfen, die Ausführung von Programm zu visualisieren
swap((a+l), (a+i)); ~~~~ Forward swap the //////// i= 0 //////// l = 0 //////// r = 2 //////// string = ABC
permute(a, l+1, r); ==== Values send to permute i.e. string= ABC //////// (l+1) = 1 //////// r = 2
swap((a+l), (a+i)); ~~~~ Forward swap the //////// i= 1 //////// l = 1 //////// r = 2 //////// string = ABC
permute(a, l+1, r); ==== Values send to permute i.e. string= ABC //////// (l+1) = 2 //////// r = 2
ABC
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swap((a+l), (a+i));++++ Backtract swap //////// i= 1 //////// l = 1 //////// r = 2 //////// string = ABC
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------------------------------END OF BACKTRACK--------------------------------------------------------------------
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swap((a+l), (a+i)); ~~~~ Forward swap the //////// i= 2 //////// l = 1 //////// r = 2 //////// string = ACB
permute(a, l+1, r); ==== Values send to permute i.e. string= ACB //////// (l+1) = 2 //////// r = 2
ACB
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swap((a+l), (a+i));++++ Backtract swap //////// i= 2 //////// l = 1 //////// r = 2 //////// string = ABC
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------------------------------END OF BACKTRACK--------------------------------------------------------------------
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swap((a+l), (a+i));++++ Backtract swap //////// i= 0 //////// l = 0 //////// r = 2 //////// string = ABC
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------------------------------END OF BACKTRACK--------------------------------------------------------------------
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swap((a+l), (a+i)); ~~~~ Forward swap the //////// i= 1 //////// l = 0 //////// r = 2 //////// string = BAC
permute(a, l+1, r); ==== Values send to permute i.e. string= BAC //////// (l+1) = 1 //////// r = 2
swap((a+l), (a+i)); ~~~~ Forward swap the //////// i= 1 //////// l = 1 //////// r = 2 //////// string = BAC
permute(a, l+1, r); ==== Values send to permute i.e. string= BAC //////// (l+1) = 2 //////// r = 2
BAC
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swap((a+l), (a+i));++++ Backtract swap //////// i= 1 //////// l = 1 //////// r = 2 //////// string = BAC
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------------------------------END OF BACKTRACK--------------------------------------------------------------------
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swap((a+l), (a+i)); ~~~~ Forward swap the //////// i= 2 //////// l = 1 //////// r = 2 //////// string = BCA
permute(a, l+1, r); ==== Values send to permute i.e. string= BCA //////// (l+1) = 2 //////// r = 2
BCA
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swap((a+l), (a+i));++++ Backtract swap //////// i= 2 //////// l = 1 //////// r = 2 //////// string = BAC
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------------------------------END OF BACKTRACK--------------------------------------------------------------------
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swap((a+l), (a+i));++++ Backtract swap //////// i= 1 //////// l = 0 //////// r = 2 //////// string = ABC
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------------------------------END OF BACKTRACK--------------------------------------------------------------------
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swap((a+l), (a+i)); ~~~~ Forward swap the //////// i= 2 //////// l = 0 //////// r = 2 //////// string = CBA
permute(a, l+1, r); ==== Values send to permute i.e. string= CBA //////// (l+1) = 1 //////// r = 2
swap((a+l), (a+i)); ~~~~ Forward swap the //////// i= 1 //////// l = 1 //////// r = 2 //////// string = CBA
permute(a, l+1, r); ==== Values send to permute i.e. string= CBA //////// (l+1) = 2 //////// r = 2
CBA
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swap((a+l), (a+i));++++ Backtract swap //////// i= 1 //////// l = 1 //////// r = 2 //////// string = CBA
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------------------------------END OF BACKTRACK--------------------------------------------------------------------
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swap((a+l), (a+i)); ~~~~ Forward swap the //////// i= 2 //////// l = 1 //////// r = 2 //////// string = CAB
permute(a, l+1, r); ==== Values send to permute i.e. string= CAB //////// (l+1) = 2 //////// r = 2
CAB
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swap((a+l), (a+i));++++ Backtract swap //////// i= 2 //////// l = 1 //////// r = 2 //////// string = CBA
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------------------------------END OF BACKTRACK--------------------------------------------------------------------
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swap((a+l), (a+i));++++ Backtract swap //////// i= 2 //////// l = 0 //////// r = 2 //////// string = ABC
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------------------------------END OF BACKTRACK--------------------------------------------------------------------
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Warum nicht ein paar hilfreiche printfs hinzufügen und dann versuchen, es läuft? –