import edu.princeton.cs.introcs.StdIn; import edu.princeton.cs.introcs.StdOut; /*********************************************************************************** * Compilation: javac MSD.java * Execution: java MSD < input.txt * * Reads extended ASCII string from standard input and MSD radix sorts them. * * % java MSD < shells.txt * are * by * sea * seashells * seashells * sells * sells * she * she * shells * shore * surely * the * the * ***********************************************************************************/ public class MSD { private static final int R = 256; // extended ASCII alphabet size private static final int CUTOFF = 15; // cutoff to insertion sort // sort array of strings public static void sort(String[] a) { int N = a.length; String[] aux = new String[N]; sort(a, 0, N-1, 0, aux); } // return dth character of s, -1 if d = length of string private static int charAt(String s, int d) { assert d >= 0 && d <= s.length(); if (d == s.length()) return -1; return s.charAt(d); } // sort from a[lo] to a[hi], starting at the dth character private static void sort(String[] a, int lo, int hi, int d, String[] aux) { // cutoff to insertion sort for small subarrays if (hi <= lo + CUTOFF) { insertion(a, lo, hi, d); return; } // compute frequency counts int[] count = new int[R+2]; for (int i = lo; i <= hi; i++) { int c = charAt(a[i], d); count[c+2]++; } // transform counts to indicies for (int r = 0; r < R+1; r++) count[r+1] += count[r]; // distribute for (int i = lo; i <= hi; i++) { int c = charAt(a[i], d); aux[count[c+1]++] = a[i]; } // copy back for (int i = lo; i <= hi; i++) a[i] = aux[i - lo]; // recursively sort for each character for (int r = 0; r < R; r++) sort(a, lo + count[r], lo + count[r+1] - 1, d+1, aux); } // return dth character of s, -1 if d = length of string private static void insertion(String[] a, int lo, int hi, int d) { for (int i = lo; i <= hi; i++) for (int j = i; j > lo && less(a[j], a[j-1], d); j--) exch(a, j, j-1); } // exchange a[i] and a[j] private static void exch(String[] a, int i, int j) { String temp = a[i]; a[i] = a[j]; a[j] = temp; } // is v less than w, starting at character d // DEPRECATED BECAUSE OF SLOW SUBSTRING EXTRACTION IN JAVA 7 // private static boolean less(String v, String w, int d) { // assert v.substring(0, d).equals(w.substring(0, d)); // return v.substring(d).compareTo(w.substring(d)) < 0; // } // is v less than w, starting at character d private static boolean less(String v, String w, int d) { assert v.substring(0, d).equals(w.substring(0, d)); for (int i = d; i < Math.min(v.length(), w.length()); i++) { if (v.charAt(i) < w.charAt(i)) return true; if (v.charAt(i) > w.charAt(i)) return false; } return v.length() < w.length(); } public static void main(String[] args) { String[] a = StdIn.readAllStrings(); int N = a.length; sort(a); for (int i = 0; i < N; i++) StdOut.println(a[i]); } }