Integrated exercises III

(総合演習 III)

Computing Practice I

14th lecture, July 12, 2018

http://www.sw.it.aoyama.ac.jp/2018/CP1/lecture14.html

Martin J. Dürst

© 2005-18 Martin J. Dürst 青山学院大学

Today's Schedule

• Remaining Schedule
• About last week's test
• About last week's exercises
• Today's exercises

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Remaining Schedule

• July 20: Integrated exercises IV
• July 27, 14:50-16:15: Term final exam (85 minutes)
• Added style switch (to show example solutions) to all past exams

Programming Contest

• Most famous student programming contest: ACM ICPC
  (Association of Computing Machinery International Collegiate Programming Contest)
• Some exercises from this contest (e.g. 1401)
• This year's Japanese preliminary was held last Friday (July 6th)
• Two teams from Aoyama Gakuin University participated
• One team qualified for next round (Yokohama in December)
• Let's participate in next year's preliminary (and finals!)
  (for example, start solving past problems in fall term)

Last Week's Exam

• Maximum: 102 points
• Average: 52.8 points
• Best result: 94 points
• Worst result: 14 points

If you have less than 40 points, please think very seriously how you can improve.

Exams will be handed back after this lecture.

Results of Previous Exercises

Total of problems solved: 4 problems: 19 students, 3 problems: 26 students, 2 problems: 45 students, 1 problems: 7 students, 0 problems: 3 student

Number of students who did not complete a single problem before 18:30: 36 students

Important Points for Application Exercises

• DRY! DRY!! DRY!!!
  
• Prefer data over code
  (Example: Use initialization instead of functions)
• Data structures matching problem structure
  (arrays, structures, combinations of arrays and structures)
• Easy to understand variable names (not just a, b, c,...)
• If labels are needed (e.g. "beef", "shrimp",...), make them part of the data
• Check which data needs to be kept across which loops
• Don't forget the basics (e.g. initialization!)

Selection of Data Structures (Example: 1303)

Data across multiple trials: none

Data common to all investment plans: duration, interest rate ⇒ single variables

Number of investment plans: Maximum 20 ⇒ array

Data per investment plan: initial investment, sales profit, operating expenses, net revenue, net present value, plan number ⇒ struct

Function vs. Initialization (Example: 1304)

Using functions:

int shrimp(int protein,int calcium)
{
    int price;
    price = protein+calcium;
    if (price>=20) return price-20;
    else           return 0;
}

Using initialization:

#define FOODS 8
#define NUTRIENTS 5
typedef struct { int nutrient[NUTRIENTS]; int price; } Food;
int main(void)
{
    Food foods[FOODS] = { { { 1, 1, 0, 0, 0}, 22 },
                          { { 0, 1, 1, 0, 0}, 20 },
                          ...
                        };
    ...
}

応用課題演習 III

今日出される問題の内、最低一問を時間内に提出、できない場合は必ず居残り、宿題を含め最低二問を完成すること

締切は全部 7月16日 (月曜日)

• 1401: カードのゲーム (複数回)
• 1402: 暗号化 (バイナリファイル入出力の応用)
• 1403: 自動販売機: 他国の紙幣構造 (例: 25¢ 硬貨) にも簡単に対応可能で DRY な設計!
• 1404: 単語の統計

解く順番は自由が、解き始めた問題は完成 (1401 からの順で推薦)

入力は問題文で説明した範囲内に限定 (エラーチェックは不要)

解け方 (アルゴリズム) は (紙などで) 例を作って実験してみる

Q&A フォーラムの活用! 題名に注意!
(問題文の詳細や解き方についての質問も勿論可能)

次回への準備

• 足りない演習問題の完成、提出
• 復習、期末試験の準備