CS 101 – Oct. 7 Solving simple problems: create algorithm Structure of solution –Sequence of steps (1,2,3….) –Sometimes we need to make a choice –Sometimes we need to repeat some steps Examples

Computer science is a problem-solving discipline. Every solution should have a well-defined structure, such as listing the ingredients and steps for input, calculations and output.

Example problems How would you solve these problems? –Print the numbers from 1 to 10. –Searching for something. In this list (3, 2, 7, 5, 4) where is the number 5? Which room contains my umbrella? –Play Tic-Tac-Toe. Idea for solution (algorithm) is more important than typing code at the keyboard.

Computer program Sequence of instructions that machine carries out Nouns and verbs Structure: –Input, calculations, output –Auxiliary functions

Kinds of statements Get input Print output Assign value to variable If-else Loop

Algorithm Clear sequence of steps to arrive at a solution to a problem. Must specify: –Input, output, variables and operations used –The order in which the steps are taken Ideally, each step should perform one calculation: –Input or output of one value –One calculation, or decision to make –Calculations usually limited to basic math –Tedious details can be put off until later.

Examples Algorithm to add two numbers –Ask the user to enter 2 values –Obtain the input, and call the values a and b. –Set a new variable sum and set it to: sum = a + b. –Output sum. Calculate weekly wage. √ –Get hours and rate from the user. –Set the wage as follows: If (hours > 40), use overtime formula Otherwise, use regular formula –Output wage