update

Task/Sorting-algorithms-Radix-sort/Java/sorting-algorithms-radix-sort.java

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+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+
+public class RSortingRadixsort00 {
+
+  public RSortingRadixsort00() {
+
+    return;
+  }
+
+  public static int[] lsdRadixSort(int[] tlist) {
+
+    List<Integer> intermediates;
+    int[] limits = getLimits(tlist);
+    tlist = rescale(tlist, limits[1]);
+
+    for (int px = 1; px <= limits[2]; ++px) {
+      @SuppressWarnings("unchecked")
+      Queue<Integer> bukits[] = new Queue[10];
+      for (int ix = 0; ix < tlist.length; ++ix) {
+        int cval = tlist[ix];
+        int digit = (int) (cval / Math.pow(10, px - 1) % 10);
+        if (bukits[digit] == null) {
+          bukits[digit] = new LinkedList<>();
+        }
+        bukits[digit].add(cval);
+      }
+
+      intermediates = new ArrayList<>();
+      for (int bi = 0; bi < 10; ++bi) {
+        if (bukits[bi] != null) {
+          while (bukits[bi].size() > 0) {
+            int nextd;
+            nextd = bukits[bi].poll();
+            intermediates.add(nextd);
+          }
+        }
+      }
+
+      for (int iw = 0; iw < intermediates.size(); ++iw) {
+        tlist[iw] = intermediates.get(iw);
+      }
+    }
+
+    tlist = rescale(tlist, -limits[1]);
+
+    return tlist;
+  }
+
+  private static int[] rescale(int[] arry, int delta) {
+
+    for (int ix = 0; ix < arry.length; ++ix) {
+      arry[ix] -= delta;
+    }
+
+    return arry;
+  }
+
+  private static int[] getLimits(int[] tlist) {
+
+    int[] lims = new int[3];
+
+    for (int i_ = 0; i_ < tlist.length; ++i_) {
+      lims[0] = Math.max(lims[0], tlist[i_]);
+      lims[1] = Math.min(lims[1], tlist[i_]);
+    }
+    lims[2] = (int) Math.ceil(Math.log10(lims[0] - lims[1]));
+
+    return lims;
+  }
+
+  private static void runSample(String[] args) {
+
+    int[][] lists = {
+      new int[] { 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, -0, -1, -2, -3, -4, -5, -6, -7, -8, -9, -10, },
+      new int[] { -10, -9, -8, -7, -6, -5, -4, -3, -2, -1, -0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, },
+      new int[] { 2, 24, 45, 0, 66, 75, 170, -802, -90, 1066, 666, },
+      new int[] { 170, 45, 75, 90, 2, 24, 802, 66, },
+      new int[] { -170, -45, -75, -90, -2, -24, -802, -66, },
+    };
+
+    long etime;
+    lsdRadixSort(Arrays.copyOf(lists[0], lists[0].length)); // do one pass to set up environment to remove it from timings
+
+    for (int[] tlist : lists) {
+      System.out.println(array2list(tlist));
+      etime = System.nanoTime();
+      tlist = lsdRadixSort(tlist);
+      etime = System.nanoTime() - etime;
+      System.out.println(array2list(tlist));
+      System.out.printf("Elapsed time: %fs%n", ((double) etime / 1_000_000_000.0));
+      System.out.println();
+    }
+
+    return;
+  }
+
+  private static List<Integer> array2list(int[] arry) {
+
+    List<Integer> target = new ArrayList<>(arry.length);
+
+    for (Integer iv : arry) {
+      target.add(iv);
+    }
+
+    return target;
+  }
+
+  public static void main(String[] args) {
+
+    runSample(args);
+
+    return;
+  }
+}