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projekti pod git sistemom za održavanje verzija -- projects under the git version control system
Simulacija rekurzije, dodatni kompleksniji primeri radjeni na casu
[spa1-materijali.git] / kodovi / simulacija-rekurzije / Rek2.java
diff --git a/kodovi/simulacija-rekurzije/Rek2.java b/kodovi/simulacija-rekurzije/Rek2.java
new file mode 100644 (file)
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@@ -0,0 +1,106 @@
+/**\r
+ * Kompleksniji primer u kome simuliramo funkciju cije funkcionisanje\r
+ * i rezultat nisu nuzno jasni.\r
+ * \r
+ * U funkciji postoje ugnjezdjeni pozivi na koje treba obratiti paznju.\r
+ * \r
+ * Ova verzija resenja takodje sadrzi i ispise parametara na 'ulazu' u\r
+ * funkciju, i iste takve kod simulirane verzije da se jasno vidi da se\r
+ * svi pozivi desavaju u istom redosledu, pri cemu su dodatno naznacene\r
+ * adrese poziva u simuliranoj verziji. Ovakav dodatak nije potreban inace\r
+ * za resavanje, ali moze pomoci u razumevanju i proveri da li je\r
+ * sve ispravno uradjeno.\r
+ */\r
+public class Rek2 {\r
+\r
+       static int g(int x, int y, int n) {\r
+               System.out.printf("0 %d %d %d\n",x,y,n);\r
+               if (n < 3) {\r
+                       return x + y;\r
+               }\r
+\r
+               if (n % 2 == 1) {\r
+                       return g(g(x + 1, y, n - 2), y, n - 3);\r
+               } else {\r
+                       return g(x, g(x, y + 1, n - 2), n - 3);\r
+               }\r
+       }\r
+\r
+       private static class InfoTip {\r
+               int x, y, n, adr;\r
+       }\r
+\r
+       static int gS(int x, int y, int n) {\r
+               int rez;\r
+               InfoTip el;\r
+               Stek<InfoTip> s = new Stek<InfoTip>();\r
+               System.out.printf("%d %d %d %d\n",0,x,y,n);\r
+\r
+               do {\r
+                       // rekurzivni spust\r
+                       while (n >= 3) {\r
+                               if (n % 2 == 1) {\r
+                                       el = new InfoTip();\r
+                                       el.x = x;\r
+                                       el.y = y;\r
+                                       el.n = n;\r
+                                       el.adr = 1;\r
+                                       s.stavi(el);\r
+                                       x = x + 1;\r
+                                       n = n - 2;\r
+                                       System.out.printf("%d %d %d %d\n",el.adr,x,y,n);\r
+                               } else {\r
+                                       el = new InfoTip();\r
+                                       el.x = x;\r
+                                       el.y = y;\r
+                                       el.n = n;\r
+                                       el.adr = 3;\r
+                                       s.stavi(el);\r
+                                       y = y + 1;\r
+                                       n = n - 2;\r
+                                       System.out.printf("%d %d %d %d\n",el.adr,x,y,n);\r
+                               }\r
+                       }\r
+\r
+                       // trivijalni slucaj\r
+                       rez = x + y;\r
+\r
+                       // povratak iz rekurzije\r
+                       boolean nemaPoziva = true;\r
+                       while (!s.jePrazan() && nemaPoziva) {\r
+                               el = s.skiniVrh();\r
+                               x = el.x;\r
+                               y = el.y;\r
+                               n = el.n;\r
+                               if (el.adr == 1) {\r
+                                       el.x = x; // nije potrebno zapravo\r
+                                       el.y = y; // nije potrebno zapravo\r
+                                       el.n = n; // nije potrebno zapravo\r
+                                       el.adr = 2;\r
+                                       s.stavi(el);\r
+                                       x = rez;\r
+                                       n = n - 3;\r
+                                       System.out.printf("%d %d %d %d\n",el.adr,x,y,n);\r
+                                       nemaPoziva = false;\r
+                               } else if (el.adr == 3) {\r
+                                       el.x = x; // nije potrebno zapravo\r
+                                       el.y = y; // nije potrebno zapravo\r
+                                       el.n = n; // nije potrebno zapravo\r
+                                       el.adr = 4;\r
+                                       s.stavi(el);\r
+                                       y = rez;\r
+                                       n = n - 3;\r
+                                       System.out.printf("%d %d %d %d\n",el.adr,x,y,n);\r
+                                       nemaPoziva = false;\r
+                               } // adr 2 i 4\r
+                                 // rez = rez; nema smisla pisati\r
+                       }\r
+               } while (!s.jePrazan());\r
+               return rez;\r
+       }\r
+\r
+       public static void main(String[] args) {\r
+               System.out.println(g(2, 3, 11));\r
+               System.out.println(gS(2, 3, 11));\r
+       }\r
+}\r
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