package eecs2030.lab6;

import java.awt.Color;
import java.util.List;

/**
 * A utility class containing recursive methods.
 * 
 * @author EECS2030 Fall 2016
 *
 */
public class Recursion {

    // DON'T ADD ANY STATIC FIELDS; YOU DON'T STATIC FIELDS AND YOUR METHODS
    // WON'T WORK CORRECTLY IF YOU USE STATIC FIELDS
    
    private Recursion() {
        // empty by design
    }
    
    /**
     * Return the sum of the integers 1 through n where n is a strictly positive integer.
     * Note that the sum might overflow if n is too large; this method does not
     * check if the sum overflows (i.e., it's the client's problem).
     * 
     * @pre n is greater than 0
     * 
     * @param n
     *            a strictly positive number
     * @return the sum 1 + 2 + ... + n
     */
    public static int sum(int n) {
        
    
    }

    /**
     * Returns a new string equal to the reversal of string s. The reversal of
     * the empty string is equal to the empty string.
     * 
     * @pre s is not null
     * 
     * @param s
     *            a string
     * @return a string equal to the reversal of s
     */
    public static String reverse(String s) {
        
    
    }

    /**
     * Returns the minimum element in the list t. This method does not modify
     * the list <code>t</code>.
     * 
     * @pre t.size() is greater than 0
     * 
     * @param t
     *            a non-empty list
     * @return the minimum element in t
     */
    public static int min(List<Integer> t) {
        
    
    }

    /**
     * Downsample a picture <code>n</code> times by a factor of 2 using
     * recursion. See the lab problem for a description of downsampling.
     * 
     * @pre the width and height of the picture are both multiples of 2 to the
     * power n
     * 
     * @pre1 n is greater than or equal to zero
     * 
     * @param p
     *            the picture to downsample
     * @param n
     *            the number of times to downsample the picture by a factor of 2
     * @return the downsampled picture
     */
    public static Picture downsample(Picture p, int n) {
        
    
    }

    /**
     * Binary search for the string <code>s</code> in a list <code>t</code>. If
     * <code>s</code> is in the list, then this method returns the index of the
     * location of <code>s</code> in <code>t</code>; otherwise, this method
     * returns the index where <code>s</code> would be located if it were to be
     * inserted into the list <code>t</code>.
     * 
     * <p>
     * This method does not modify the list <code>t</code>.
     * 
     * @pre t.size() is zero or more 
     * @pre1 t is in sorted order 
     * @pre2 t has no duplicate elements
     * 
     * @param s
     *            a string
     * @param t
     *            a list
     * @return the index of s if s is in the list; otherwise, returns the index
     *         where s would be located if it were to be inserted into the list
     */
    public static int bsearch(String s, List<String> t) {
        
    
    }

    public static void main(String[] args) {
        // RUN THIS TO TEST downsample
        Picture p = new Picture("snowflake.jpg");
        p.show();
        downsample(p, 1).show();
        downsample(p, 2).show();
        downsample(p, 3).show();
    }
}