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![public long convertToNumericIp(String ip) {
long numericIp = 0;
String[] octets = ip.split(“.");
for (int i = 0; i < 4; ++i)
numericIp += parseInt(octets[i]) * Math.pow(256, 3 - i);
return numericIp;
}
243.131.122.231
243*256*256*256 + 131*256*256 + 122*256 + 231
= 4085480167](https://image.slidesharecdn.com/problemsolving-190927015802/75/Problem-Solving-Techniques-For-Evolutionary-Design-25-2048.jpg)
![def move(players, player_turn)
new_position = players[player_turn] + throw_dice
new_position = @snakes_ladders[new_position]
if @snakes_ladders.has_key?(new_position)
return player_turn if new_position >= @board_size
players[player_turn] = new_position
next_player = (player_turn + 1) % players.length
move(players, next_player)
end
https://github.com/nashjain/snakes_n_ladders](https://image.slidesharecdn.com/problemsolving-190927015802/75/Problem-Solving-Techniques-For-Evolutionary-Design-28-2048.jpg)
![public long convertToNumericIp(String ip) {
long numericIp = 0;
String[] octets = ip.split(“.");
for (int i = 0; i < 4; ++i)
numericIp += parseInt(octets[i]) * Math.pow(256, 3 - i);
return numericIp;
}
243.131.122.231
243*256*256*256 + 131*256*256 + 122*256 + 231
= 4085480167](https://crownmelresort.com/image.slidesharecdn.com/problemsolving-190927015802/75/Problem-Solving-Techniques-For-Evolutionary-Design-25-2048.jpg)
![def move(players, player_turn)
new_position = players[player_turn] + throw_dice
new_position = @snakes_ladders[new_position]
if @snakes_ladders.has_key?(new_position)
return player_turn if new_position >= @board_size
players[player_turn] = new_position
next_player = (player_turn + 1) % players.length
move(players, next_player)
end
https://github.com/nashjain/snakes_n_ladders](https://crownmelresort.com/image.slidesharecdn.com/problemsolving-190927015802/75/Problem-Solving-Techniques-For-Evolutionary-Design-28-2048.jpg)
Uploaded byNaresh Jain
Problem Solving Techniques For Evolutionary Design
The document discusses various problem-solving techniques and strategies relevant to evolutionary design, including rounding logic for billing applications and hotel charge calculation methods. It also provides code examples for games like Snakes and Ladders, IP address range determination, and medical age representation. Key strategies emphasized are sandboxing, brainstorming, and divide and conquer, alongside practical advice for solving complex problems.
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Problem Solving Techniques For Evolutionary Design
- 1. Problem Solving Techniques ForEvolutionary Design Distilling Down Any Problem to Its Crux Naresh Jain naresh@xnsio.com @nashjain https://xnsio.com
- 2. Rounding Up tothe Closest 5 Cents • In my billing application • Given the price of an item comes up to $20.23 after tax • I want to round up 23 cents to the closest 5 cents denomination .i.e. 25 cents • So I can charge $20.25 • https://github.com/nashjain/rounding_logic • https://help.github.com/categories/54/articles
- 3. Tests @Test public void shouldLeaveAsIsIfAlreadyInDenominationsOf5Cents(){ assertEquals(20.25, round(20.25), 0.01); } @Test public void shouldRoundUpToNext5Cents() { assertEquals(20.25, round(20.24), 0.01); } @Test public void shouldRoundUpEvenIfAmountIsLessThanPoint023() { assertEquals(20.25, round(20.21), 0.01); } https://github.com/nashjain/rounding_logic
- 4. Rounding Up -Answer • var price = 20.23; • var rounded_price = ceil(price / 0.05) * 0.05; or • var rounded_price = ceil(price * 20) / 20;
- 5. Hotel Room Charge •Calculate the bill amount based on the number of hotel nights the guest has stayed in the hotel. • Per hotel night is charged at 4999 INR for single occupancy and 5499 INR for double occupancy. • Hotels have a standard 12:00 noon checkin and checkout. • Early Checkin: Guest can request to checkin early (before 12:00 noon.) If they checkin between 9 and 12, they are charged 50% extra. If they checkin before 9 AM, then they are charged full night charge. • Late Checkout: Guest can request a late checkout. If they checkout after 12 noon and before 3, they are charged 50% extra and if they checkout after 3:00 PM, they have to pay one whole night's extra charge.
- 6. function calculate_hotel_charge(occupancy, hotel_checkin,hotel_checkout) { var per_night_rate = occupancy == ‘Single’ ? 4999 : 5499; return per_night_rate * total_nights(hotel_checkin, hotel_checkout); } function total_nights(hotel_checkin, hotel_checkout) { return max(actual_nights(hotel_checkin, hotel_checkout) + early_checkin_nights(hotel_checkin) + late_checkout_nights(hotel_checkout), 1); } function actual_nights(hotel_checkin, hotel_checkout) { return floor((hotel_checkout - hotel_checkin) / (24 * 60 * 60 * 1000)); } functional early_checkin_nights(hotel_checkin) { if(hotel_checkin.getHours() > 12) return 0; if(hotel_checkin.getHours() > 9) return 0.5; return 1; } Hotel Room Charge Solution functional late_checkout_nights(hotel_checkout) { if(hotel_checkin.getHours() < 12) return 0; if(hotel_checkin.getHours() < 3) return 0.5; return 1; }
- 7. High-level Approach Eliminate NoiseDivide & Conquer Test Data Constraints Simple Design Manual Debug Refactor Throw Away Create Add Come up with Simplify the Problem Prioritise Remove constrains Works? More Constraints Exit? Yes No
- 8. Problem-Solving Strategies • Sandboxing:solving the problem in a model of the system before applying it to the real system • Metaphor: using a solution that solves an analogous problem • Brainstorming: exploring a large number of solutions or ideas and combining and developing them until an optimum solution is found • Divide and conquer: breaking down a large, complex problem into smaller, solvable problems • Hypothesis testing: assuming a possible explanation to the problem and trying to prove (or disprove) the assumption • Reduction: transforming the problem into another problem for which solutions exist • Trial-and-error: testing possible solutions until the right one’s Adapted from: http://en.wikipedia.org/wiki/Problem_solving#Problem-solving_strategies
- 9.
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- 23. IP Address Range •Each country has blocks of IPv4 address range assigned to it • Given I have an IP address I want to figure out which country it belong to
- 24. Start End TotalIPs Country 1.6.0.0 1.7.255.255 131072 India 1.22.0.0 1.23.255.255 131072 India 1.186.0.0 1.186.255.255 65536 India 1.0.32.0 1.0.63.255 8192 China 1.1.16.0 1.1.31.255 4096 China 1.4.16.0 1.4.31.255 4096 Japan • https://github.com/nashjain/ip2country • 196 countries with 100s of such blocks
- 25. public long convertToNumericIp(Stringip) { long numericIp = 0; String[] octets = ip.split(“."); for (int i = 0; i < 4; ++i) numericIp += parseInt(octets[i]) * Math.pow(256, 3 - i); return numericIp; } 243.131.122.231 243*256*256*256 + 131*256*256 + 122*256 + 231 = 4085480167
- 27. Snakes and Ladders •One or more players can play the game • Typical board size is 10 x10, but user can specify different board size • User can decide the game mode (Easy = 5 snakes and ladders, Medium = 10 snakes and ladders, Hard = 20 snakes and ladders.) Default to easy mode. • After each move, snakes and ladders could move, but at least after each game, they should move. • Game takes the names of all the players and reports the name of the winner. • Random player gets to start
- 28. def move(players, player_turn) new_position= players[player_turn] + throw_dice new_position = @snakes_ladders[new_position] if @snakes_ladders.has_key?(new_position) return player_turn if new_position >= @board_size players[player_turn] = new_position next_player = (player_turn + 1) % players.length move(players, next_player) end https://github.com/nashjain/snakes_n_ladders
- 29. Medical Age Printer AgeReported in Greater than 1Year <Patient Name> is #Years old > 1 Month & < 1Year <Patient Name> is # Months old > 1 Day & < 1 Month <Patient Name> is # Days old > 1 Hr & < 1 Day <Patient Name> is # Hours old Doctors and Nurses might like to add and remove new Durations. For Ex: If they add Decade, and Patient’s age is greater than 10 years, then age should be reported as <Patient Name> is # Decades old. Similarly: If they add Week, and Patient’s age is greater than 7 Day, but less than a month, then age should be reported as <Patient Name> is # Weeks old. https://github.com/nashjain/map
- 30. private static finallong MILLIS_IN_MIN = 60 * 1000L; private static final long MILLIS_IN_HOUR = MILLIS_IN_MIN * 60; private static final long MILLIS_IN_DAY = MILLIS_IN_HOUR * 24; private static final long MILLIS_IN_MONTH = MILLIS_IN_DAY * 30; private static final long MILLIS_IN_YEAR = MILLIS_IN_DAY * 365; private final TreeMap<Long, String> millisPerUnit = new TreeMap<Long, String>() { { put(MILLIS_IN_HOUR, "Hours"); put(MILLIS_IN_DAY, "Days"); put(MILLIS_IN_MONTH, "Months"); put(MILLIS_IN_YEAR, "Year"); } }; public String since(Date dob) { long deltaInMillis = differenceInMillisFromNow(dob); Entry<Long, String> duration = millisPerUnit.floorEntry(deltaInMillis); if (duration == null) return "0 Hours"; return deltaInMillis / duration.getKey() + " " + duration.getValue(); } private long differenceInMillisFromNow(Date date) { return clock.now() - date.getTime(); }
- 31. Recap Eliminate Noise Divide& Conquer Test Data Constraints Simple Design Manual Debug Refactor Throw Away Create Add Come up with Simplify the Problem Prioritise Remove constrains Works? More Constraints Exit? Yes No
- 32.
- 33. Pick a Solutionafter Trying at least 3 Approaches
- 34. "Perfection (in design)is achieved not when there is nothing more to add, but rather when there is nothing more to take away." – Eric S Raymond
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- 38. Practice An HourEach Day
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