teaching machines

CS 145 Lecture 3 – Algorithms

February 1, 2012 by Chris Johnson. Filed under cs145, lectures, spring 2012.

Agenda

• algorithm
• pseudocode
• program this
• an early algorithm, a la Euclid
• primitives have operators
• objects have methods
• API
• String methods

Program this

You are indecisive. So are your friends. One quiet Monday night, you all decide one night to come up with a list of restaurants, each accompanied by a probability of how often you go there. The weekend comes. Where do you go?

Code

CellBill.java

package preexam1;

import java.util.Scanner;

public class CellBill {
  public static void main(String[] args) {
    // figure out how many people there are
    // find out bill 1, add to running sum
    // find out bill 2, add to running sum
    // find out bill ..., add 
    // find out bill 8
    // divide total by number of people
    // print result
    
    final int nPeople = 8;
    Scanner in = new Scanner(System.in);
    
    double runningSum = 0.0;
    
    runningSum = runningSum + in.nextDouble();
    runningSum = runningSum + in.nextDouble();
    runningSum = runningSum + in.nextDouble();
    runningSum = runningSum + in.nextDouble();
    runningSum = runningSum + in.nextDouble();
    runningSum = runningSum + in.nextDouble();
    runningSum = runningSum + in.nextDouble();
    runningSum = runningSum + in.nextDouble();

    double average = runningSum / nPeople;
    System.out.println("Average: " + average);
  }
}

MaxSiblings.java

package preexam1;

import java.util.Scanner;

public class MaxSiblings {
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    
    int maxSiblings = 0;
    
    maxSiblings = Math.max(maxSiblings, in.nextInt());
    maxSiblings = Math.max(maxSiblings, in.nextInt());
    maxSiblings = Math.max(maxSiblings, in.nextInt());
    maxSiblings = Math.max(maxSiblings, in.nextInt());

    maxSiblings = Math.max(maxSiblings, in.nextInt());
    maxSiblings = Math.max(maxSiblings, in.nextInt());
    maxSiblings = Math.max(maxSiblings, in.nextInt());
    maxSiblings = Math.max(maxSiblings, in.nextInt());

    System.out.println("Max: " + maxSiblings);
  }
}

StringMethods.java

package preexam1;

public class StringMethods {
  public static void main(String[] args) {
    String email = "johnchamp@uwec.edu";
    
    System.out.println(email.length());
    System.out.println(email.charAt(0));
  }
}

Haiku