tasks a-s

Task/Permutations/XPL0/permutations.xpl0

@@ -0,0 +1,25 @@
+code ChOut=8, CrLf=9;
+def  N=4;                       \number of objects (letters)
+char S0, S1(N);
+
+proc Permute(D);                \Display all permutations of letters in S0
+int D;                          \depth of recursion
+int I, J;
+[if D=N then
+        [for I:= 0 to N-1 do ChOut(0, S1(I));
+        CrLf(0);
+        return;
+        ];
+for I:= 0 to N-1 do
+        [for J:= 0 to D-1 do    \check if object (letter) already used
+                if S1(J) = S0(I) then J:=100;
+        if J<100 then
+                [S1(D):= S0(I); \object (letter) not used so append it
+                Permute(D+1);   \recurse next level deeper
+                ];
+        ];
+];
+
+[S0:= "rose ";                  \N different objects (letters)
+Permute(0);                     \(space char avoids MSb termination)
+]