/****************************************************************************** * Compilation: javac InsertionPedantic.java * Execution: java InsertionPedantic < input.txt * Dependencies: StdOut.java StdIn.java * Data files: https://algs4.cs.princeton.edu/21elementary/tiny.txt * https://algs4.cs.princeton.edu/21elementary/words3.txt * * Sorts a sequence of strings from standard input using insertion sort. * * Can pass either an array of Comparables, or an array of Objects * along with a Comparator. * * Uses static generics to avoid compile-time warnings. * * * % more tiny.txt * S O R T E X A M P L E * * % java InsertionPedantic < tiny.txt * A E E L M O P R S T X [ one string per line ] * * % more words3.txt * bed bug dad yes zoo ... all bad yet * * % java InsertionPedantic < words3.txt * all bad bed bug dad ... yes yet zoo [ one string per line ] * ******************************************************************************/ import java.util.Comparator; public class InsertionPedantic { // using natural order and Comparable interface public static > void sort(Key[] a) { int n = a.length; for (int i = 1; i < n; i++) for (int j = i; j > 0 && less(a[j], a[j-1]); j--) exch(a, j, j-1); } // using custom-order and Comparator interface public static void sort(Key[] a, Comparator comparator) { int n = a.length; for (int i = 1; i < n; i++) for (int j = i; j > 0 && less(comparator, a[j], a[j-1]); j--) exch(a, j, j-1); } public static > int[] indexSort(Key[] a) { int n = a.length; int[] index = new int[n]; for (int i = 0; i < n; i++) index[i] = i; for (int i = 1; i < n; i++) for (int j = i; j > 0 && less(a[index[j]], a[index[j-1]]); j--) exch(index, j, j-1); return index; } /*************************************************************************** * Helper sorting functions. ***************************************************************************/ // is v < w ? private static > boolean less(Key v, Key w) { return v.compareTo(w) < 0; } // is v < w? private static boolean less(Comparator comparator, Key v, Key w) { return comparator.compare(v, w) < 0; } // no need for generics here private static void exch(Object[] a, int i, int j) { Object swap = a[i]; a[i] = a[j]; a[j] = swap; } // exchange a[i] and a[j] private static void exch(int[] a, int i, int j) { int swap = a[i]; a[i] = a[j]; a[j] = swap; } /*************************************************************************** * Check if array is sorted - useful for debugging. ***************************************************************************/ private static > boolean isSorted(Key[] a) { for (int i = 1; i < a.length; i++) if (less(a[i], a[i-1])) return false; return true; } // print array to standard output private static void show(Comparable[] a) { for (int i = 0; i < a.length; i++) { StdOut.println(a[i]); } } // Read strings from standard input, sort them, and print. public static void main(String[] args) { String[] a = StdIn.readAllStrings(); sort(a); show(a); assert isSorted(a); } }