/****************************************************************************** * Compilation: javac Count.java * Execution: java Count alpha < input.txt * Dependencies: Alphabet.java StdOut.java * Data files: https://algs4.cs.princeton.edu/50strings/abra.txt * https://algs4.cs.princeton.edu/50strings/pi.txt * * Create an alphabet specified on the command line, read in a * sequence of characters over that alphabet (ignoring characters * not in the alphabet), computes the frequency of occurrence of * each character, and print out the results. * * % java Count ABCDR < abra.txt * A 5 * B 2 * C 1 * D 1 * R 2 * * % java Count 0123456789 < pi.txt * 0 99959 * 1 99757 * 2 100026 * 3 100230 * 4 100230 * 5 100359 * 6 99548 * 7 99800 * 8 99985 * 9 100106 * ******************************************************************************/ /** * The {@code Count} class provides an {@link Alphabet} client for reading * in a piece of text and computing the frequency of occurrence of each * character over a given alphabet. *

* For additional documentation, * see Section 5.5 of * Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne. * * @author Robert Sedgewick * @author Kevin Wayne */ public class Count { // Do not instantiate. private Count() { } /** * Reads in text from standard input; calculates the frequency of * occurrence of each character over the alphabet specified as a * command-line argument; and prints the frequencies to standard * output. * * @param args the command-line arguments */ public static void main(String[] args) { Alphabet alphabet = new Alphabet(args[0]); final int R = alphabet.radix(); int[] count = new int[R]; while (StdIn.hasNextChar()) { char c = StdIn.readChar(); if (alphabet.contains(c)) count[alphabet.toIndex(c)]++; } for (int c = 0; c < R; c++) StdOut.println(alphabet.toChar(c) + " " + count[c]); } }