Data commit

Task/Permutations-by-swapping/Zkl/permutations-by-swapping-1.zkl

@@ -0,0 +1,13 @@
+fcn permute(seq)
+{
+   insertEverywhere := fcn(x,list){ //(x,(a,b))-->((x,a,b),(a,x,b),(a,b,x))
+      (0).pump(list.len()+1,List,'wrap(n){list[0,n].extend(x,list[n,*]) })};
+   insertEverywhereB := fcn(x,t){ //--> insertEverywhere().reverse()
+      [t.len()..-1,-1].pump(t.len()+1,List,'wrap(n){t[0,n].extend(x,t[n,*])})};
+
+   seq.reduce('wrap(items,x){
+      f := Utils.Helpers.cycle(insertEverywhereB,insertEverywhere);
+      items.pump(List,'wrap(item){f.next()(x,item)},
+	      T.fp(Void.Write,Void.Write));
+   },T(T));
+}

Task/Permutations-by-swapping/Zkl/permutations-by-swapping-2.zkl

@@ -0,0 +1,6 @@
+p := permute(T(1,2,3));
+p.println();
+
+p := permute([1..4]);
+p.len().println();
+p.toString(*).println()

Task/Permutations-by-swapping/Zkl/permutations-by-swapping-3.zkl

@@ -0,0 +1,21 @@
+ fcn [private] _permuteW(seq){	// lazy version
+   N:=seq.len(); NM1:=N-1;
+   ds:=(0).pump(N,List,T(Void,-1)).copy(); ds[0]=0; // direction to move e: -1,0,1
+   es:=(0).pump(N,List).copy();  // enumerate seq
+
+   while(1) {
+      vm.yield(es.pump(List,seq.__sGet));
+
+      // find biggest e with d!=0
+      reg i=Void, c=-1;
+      foreach n in (N){ if(ds[n] and es[n]>c) { c=es[n]; i=n; } }
+      if(Void==i) return();
+
+      d:=ds[i]; j:=i+d;
+      es.swap(i,j); ds.swap(i,j);	// d tracks e
+      if(j==NM1 or j==0 or es[j+d]>c) ds[j]=0;
+      foreach e in (N){ if(es[e]>c) ds[e]=(i-e).sign }
+   }
+}
+
+fcn permuteW(seq) { Utils.Generator(_permuteW,seq) }

Task/Permutations-by-swapping/Zkl/permutations-by-swapping-4.zkl

@@ -0,0 +1 @@
+foreach p in (permuteW(T("a","b","c"))){ println(p) }