package edu.princeton.cs.algs4.ch31;
import edu.princeton.cs.algs4.ch13.Queue;
import edu.princeton.cs.introcs.StdIn;
import edu.princeton.cs.introcs.StdOut;
/*************************************************************************
* Compilation: javac ArrayST.java
* Execution: java ArrayST < input.txt
* Dependencies: StdIn.java StdOut.java
* Data files: http://algs4.cs.princeton.edu/31elementary/tinyST.txt
*
*
* Symbol table implementation with unordered array. Uses repeated
* doubling to resize the array.
*
* % java ArrayST < tiny.txt
* S 0
* H 5
* X 7
* R 3
* C 4
* L 11
* A 8
* M 9
* P 10
* E 12
*
*************************************************************************/
public class ArrayST<Key, Value> {
private static final int INIT_SIZE = 8;
private Value[] vals; // symbol table values
private Key[] keys; // symbol table keys
private int N = 0; // number of elements in symbol table
public ArrayST() {
keys = (Key[]) new Object[INIT_SIZE];
vals = (Value[]) new Object[INIT_SIZE];
}
// return the number of key-value pairs in the symbol table
public int size() { return N; }
// is the symbol table empty?
public boolean isEmpty() { return size() == 0; }
// resize the parallel arrays to the given capacity
private void resize(int capacity) {
Key[] tempk = (Key[]) new Object[capacity];
Value[] tempv = (Value[]) new Object[capacity];
for (int i = 0; i < N; i++) tempk[i] = keys[i];
for (int i = 0; i < N; i++) tempv[i] = vals[i];
keys = tempk;
vals = tempv;
}
// insert the key-value pair into the symbol table
public void put(Key key, Value val) {
// to deal with duplicates
delete(key);
// double size of arrays if necessary
if (N >= vals.length) resize(2*N);
// add new key and value at the end of array
vals[N] = val;
keys[N] = key;
N++;
}
public Value get(Key key) {
for (int i = 0; i < N; i++)
if (keys[i].equals(key)) return vals[i];
return null;
}
public Iterable<Key> keys() {
Queue<Key> queue = new Queue<Key>();
for (int i = 0; i < N; i++)
queue.enqueue(keys[i]);
return queue;
}
// remove given key (and associated value)
public void delete(Key key) {
for (int i = 0; i < N; i++) {
if (key.equals(keys[i])) {
keys[i] = keys[N-1];
vals[i] = vals[N-1];
keys[N-1] = null;
vals[N-1] = null;
N--;
if (N > 0 && N == keys.length/4) resize(keys.length/2);
return;
}
}
}
/***********************************************************************
* Test routine.
**********************************************************************/
public static void main(String[] args) {
ArrayST<String, Integer> st = new ArrayST<String, Integer>();
for (int i = 0; !StdIn.isEmpty(); i++) {
String key = StdIn.readString();
st.put(key, i);
}
for (String s : st.keys())
StdOut.println(s + " " + st.get(s));
}
}