Here are all the past problems for the NOI.PH. Trying this out should give you a glimpse of what NOI problems are like. If you get stumped, you should prepare by reading the resources on this website.
If you can’t access the past problems, click here.
| id | problem | year | type |
|---|---|---|---|
| 0 | Azalea A fresh new start, and a new introduction to the NOI.PH! | 2017 | S |
| 1 | Aguinaldo Can you keep track of Emilio's gifts? | 2016 | S |
| 2 | Who is the oldest? Determine the oldest among friends. | 2014 | PR |
| 3 | Sharing Chocolates Can Alvin and Berto share their chocolates fairly? | 2014 | PR |
| 4 | Sharing Chocolates 2: A Charity Event Our favorite bro-grammers take sharing to a whole new level. | 2014 | F0 |
| 5 | Sharing Chocolates 3: World Record Alvin and Berto set out to beat the current chocolate-eating world record. | 2015 | F0 |
| 6 | On pamelas and pomelos Which of the Pamelas is closest to the pomelo? | 2014 | F1 |
| 7 | Body Mass Index Help Payton find out whether he should go on a diet. | 2014 | E1 |
| 8 | A Simple Problem. This is a simple problem. | 2016 | F0 |
| 9 | Sharing Chocolates 4: A New Chocolate Not so long ago, in a factory not so far far away. | 2016 | F0 |
| 10 | The Playground Fights Help the teacher in dealing with kindergarteners. | 2014 | PR |
| 11 | The Slippery Slope Help Cassandra climb the slippery slope! | 2014 | PR |
| 12 | Jade N. Smith Tweets How Can This Problem Be Real If Our Eyes Aren’t Real? | 2014 | F0 |
| 13 | Union Find Guess which algorithm you’ll have to use for this problem! | 2016 | F0 |
| 14 | Family Three sisters discover where to find the true treasure within. | 2014 | E1 |
| 15 | xoxo Find out who won in a game of xoxo. | 2014 | F1 |
| 16 | 1 Like = 1 House Like! Share! Comment! Change the World! | 2016 | T1 |
| 17 | The Final Schwelve It's not The Final Twelve. It's the Final Schwelve. | 2015 | F2 |
| 18 | Meteor Garden Garden The boys are fighting over flowers in this Asianovela-inspired problem! | 2016 | E2 |
| 19 | Extreme Triangle Help Shan win the game Extreme Triangle. | 2014 | PR |
| 20 | Path in a Maze Find the path through the maze. | 2014 | F0 |
| 21 | In or Out In or out? Can I stay in or do I have to go out? | 2015 | F0 |
| 22 | Make Gawa This Program Please make gawa this program. | 2015 | T3 |
| 23 | Onion Find Guess which vegetable this problem is about! | 2016 | F0 |
| 24 | Tataramon In this problem. we encourage you to be the very best like no one ever was! | 2016 | T2 |
| 25 | Ham Path Help Ham the hamster explore Hamsterdam. | 2015 | F0 |
| 26 | Shake It Off Make the program up as you go read Taylor's problem. | 2016 | F2 |
| 27 | Awit2DARemixYo!: To The Remix Here's a problem remixing the problem about the new type of poetry form made by Joseph and Mariah. | 2016 | T3 |
| 28 | A Problem Made By Fools Like Me I think that I shall never see, \\ A poem as lovely as an integer whose hundreds digit is a 3. | 2016 | T1 |
| 29 | Friday I need a schedule on when to wear my tinfoil hat. | 2015 | T1 |
| 30 | Rectangle, Diagonal, Perimeter Find the maximum perimeter of a rectangle whose diagonal length is given. | 2014 | E1 |
| 31 | Bounce Bounce Bounce How many ways can you make a laser bounce bounce bounce? | 2014 | E1 |
| 32 | Running Sam Help Sam in his self-made mental challenge. | 2015 | F1 |
| 33 | Stones on a Board Find out how many ways Jeff can arrange his stones on a board. | 2014 | PR |
| 34 | Modified Flames Experience our beloved childhood game with a twist! | 2016 | T2 |
| 35 | A Packing Problem Can Miguel pack the cans properly? | 2014 | F1 |
| 36 | 런데빌런 What is the maximum and minimum velocity of 데빌? | 2016 | E1 |
| 37 | Hasht5 Numbers Compute Hasht5 numbers. | 2016 | T3 |
| 38 | What Day is It? Never let a rainy day or a Juday get you down! | 2015 | F1 |
| 39 | Pick-Up Battle Compute scores in the Pick-Up Battle. | 2016 | T1 |
| 40 | Banana Queue Everyone's going bananas in this exciting work shift! | 2015 | T5 |
| 41 | Bureaucracy is Fun It's a good thing you don't need to fill in a form every time you make a submission! | 2016 | T2 |
| 42 | A Simple Problem! This is a simple problem! | 2016 | F1 |
| 43 | Alien Defense Help the inhabitants of Informatica defend against the alien invasion! | 2014 | PR |
| 44 | Pabebe Girl Cuts Cake How many ways can a Pabebe Girl cut a rectangular mamon? | 2016 | F1 |
| 45 | Putogethers How many mash-ups can the organizers of the annual puto festival make? | 2016 | E1 |
| 46 | Burning Bridges The newly-appointed king of the archipelago seems to be the type who likes to burn bridges instead of making friends. | 2014 | E1 |
| 47 | The King and Queen of Rock and Roll Could the interior designer make a proper floor plan following the conditions of the king and queen of Rock and Roll? | 2016 | F1 |
| 48 | Tinikling 2: The Sequel Help Cleverlyn devise a clever way to adapt to this awkward situation! | 2016 | T3 |
| 49 | Dili Magpakopya Honesty is the best policy. | 2015 | F1 |
| 50 | Paasa Numbers List down all the paasa numbers to make the world a better place! | 2016 | F2 |
| 51 | Awit2DARemixYo! Joseph and Mariah make a new type of poetry form! | 2015 | E1 |
| 52 | Candies for Everyone Find out how candies are distributed among the students. | 2014 | PR |
| 53 | Kawaii How many ways can I help Senpai such that I do not produce a bakemono, avoid being itai and not be called a taidana? | 2015 | T3 |
| 54 | Burning Bridges [Redux] The newly-appointed king of the archipelago seems to be the type who likes to burn bridges instead of making friends. | 2016 | T3 |
| 55 | Chuva Choo Choo Make your crush feel like he/she is in heaven by giving him/her a mix tape! | 2015 | F2 |
| 56 | Christopher's Candy Chaos Help Christopher with a promo for his store. | 2014 | E1 |
| 57 | Expert Timing This is the cooking test for NOIPH. | 2016 | E3 |
| 58 | Bob's Prob Be part of Bob's life-changing experience. | 2014 | PR |
| 59 | Color Grid After doing a bunch of stuff, how many cells of each color will the grid have? | 2014 | E1 |
| 60 | The Questions I Ask Myself Help me answer the questions I ask myself. | 2014 | F1 |
| 61 | A Little Bit Frightening This is the sculpting test for NOIPH. | 2016 | E3 |
| 62 | Cheesus I hope you're not lactose-intolerant since this is going to be a very cheesy problem! | 2015 | T2 |
| 63 | Traveling Supermodel Problem Can the supermodels find the most fabulous path? | 2014 | PR |
| 64 | Candies for Everyone [Redux] Find out how candies are distributed among the students. | 2016 | T1 |
| 65 | Farm Wars Find the optimal strategy for Farm Wars. | 2014 | PR |
| 66 | This Problem Is So Fetch How much did Rob's opinion change about whether Payton is fetch? | 2015 | E2 |
| 67 | The Modular Wizard Help Jwrhla compute a number modulo 10^9. | 2016 | T1 |
| 68 | Balikbayan Boxes Optimize your way around the airport! | 2016 | E2 |
| 69 | Carps? Pics. | 2016 | F3 |
| 70 | The RSA Cryptosystem Given an interval, how many numbers satisfy a certain property? | 2014 | F1 |
| 71 | Christopher's Candy Chaos [Redux] Help Christopher with a promo for his store. | 2015 | T1 |
| 72 | Bob's Prob [Redux] Be part of Bob's life-changing experience. | 2015 | T2 |
| 73 | Christmas at NAIA Though it was once rated as the worst airport, NAIA personnel have brushed that reputation aside by being generous to the travelers, especially this holiday season! | 2016 | E2 |
| 74 | Supkotao Spukotao plays a prank in his office. | 2015 | E1 |
| 75 | Kambyo Kard Use your Kambyo Kard wisely. | 2015 | E1 |
| 76 | The RSA Cryptosystem [Redux] Given an interval, how many numbers satisfy a certain property? | 2015 | T5 |
| 77 | Lonely People in the World Who are the lonely people in the world? | 2015 | T2 |
| 78 | Introductions Take out your social ladders because we're going to go social climbing! | 2016 | T2 |
| 79 | All for Nine and Nine for All How many ways can you win in this new Lunchtime Surprise game? | 2014 | F1 |
| 80 | Confidential Message Yuo received a message but it was jumbled by some confidential process. | 2016 | F1 |
| 81 | Lolcuts How cud u cut thees? | 2015 | T4 |
| 82 | Jabahw A very bias problem. | 2016 | F3 |
| 83 | Kung-Fu Fighting This is the Kung-Fu test for NOIPH. | 2016 | E3 |
| 84 | The Holiday School Play Let's assign roles to everyone for the holiday school play! | 2016 | E1 |
| 85 | Goodbye, Awkward Goodbyes! Help Martin and Martin figure out the correct place to say goodbye. | 2016 | F2 |
| 86 | Escape the Temple You got in the temple. Now, how do you get out? | 2015 | T5 |
| 87 | Tinikling 2 Can a dancer navigate the bamboo pole puzzle to the beat of the music? | 2015 | E2 |
| 88 | World Peace How skillful must you be to retrieve The Artifact of World Peace? | 2014 | F1 |
| 89 | HeKaSerye #LUNAYSIDRANoongUnangPanahon | 2016 | E2 |
| 90 | Dishes: How We Do It? How many ways are there to assign dishes to the islands of King Manuel VI's archipelago? | 2016 | E1 |
| 91 | Chooga Choo Choo Get the scores of Cheech and Chong during their games in a train. | 2015 | F2 |
| 92 | Color Grid [Redux] After doing a bunch of stuff, how many cells of each color will the grid have? | 2015 | T3 |
| 93 | Alien Defense Deux Find the number of laser-strike-free square areas. | 2015 | T1 |
| 94 | Super Boss Use your stick and get some balls to defeat the Super Boss! | 2015 | F2 |
| 95 | Big Balls Guess the weights of the balls from comparisons. | 2014 | E1 |
| 96 | Skwishinese Determine how beautiful a Skwishinese word is. | 2014 | E1 |
| 97 | Zognoid Eggs Don't be mad, don't be sad! | 2016 | F3 |
| 98 | Reverse Trip to Jerusalem Winning in Trip to Jerusalem is so two thousand and late. Winning Reverse Trip to Jerusalem is what matters. | 2014 | PR |
| 99 | Balot Boxes Help the balot watchers maintain the integrity of the contest. | 2016 | F3 |
| 100 | World Peace [Redux] How skillful must you be to retrieve The Artifact of World Peace? | 2015 | T4 |
| 101 | The Tide is High Compute the productivity of an archipelago when the tide is high. | 2016 | T1 |
| 102 | Chooga Choo Choo [Redux] Get the scores of Cheech and Chong during their games in a train. | 2016 | T3 |
| 103 | House Arrest Help Jejeman find the best lot for his house arrest. | 2015 | E2 |
| 104 | PWNED BY ANONYMOUS PH PWNED BY ANONYMOUS PH | 2016 | F3 |
| 105 | Candles for Everyone But where's the cake? | 2016 | F2 |
| 106 | All About the Base How many cans do we need to satisfy both Vladonis and Vladiana? | 2015 | T4 |
| 107 | Yumamma Help Yumamma! | 2016 | T2 |
| 108 | Fast As Lightning This is the lattice test for NOIPH. | 2016 | E3 |
| 109 | David Copperfailed Find the number of quadruples where the magic trick works. | 2014 | E1 |
| 110 | Oprah's Favorite Things How many of each favorite thing should Oprah buy to maximize the gift certificate? | 2014 | F1 |
| 111 | Back to the Future You wanted to build a clock but you ended up with a time machine. Close enough. | 2015 | E2 |
| 112 | Guardians of the Lunatics Assign the guards to minimize the risk that a lunatic might escape! | 2014 | F1 |
| 113 | The Grand Noi and ICPC Battle Help the Noi defeat their wicked foes, the ICPCs. | 2014 | F1 |
| 1701 | Pak Ganern For every `PAK` there is an equal and opposite `GANERN`. | 2017 | E |
| 1702 | Copy Pasta Can you figure out how many copy pasta resulted in an unfortunate accident? | 2017 | E |
| 1703 | Ati-atihan Dance Party At any given time, how many audience members are engaged by the performers? | 2017 | E |
| 1704 | Cargo Train to Busan Help Seok-woo determine how much safe space there is in each carriage so that he can spend his energy wisely. | 2017 | E |
| 1705 | Mutual Friendzone How many mutual friendships in the peculiar friendship network? | 2017 | E |
| 1706 | Another Packing Problem Can Miguel answer his packing question? | 2017 | E |
| 1707 | Hidden Pepe It all started with a hidden Pepe. | 2017 | E |
| 1708 | The Cheapest Reid Help James and Nadine go from city A to city B in the cheapest way possible! | 2017 | E |
| 1709 | Goodboy Goodboy wants to be a good boy by reporting absentees to the school administration. | 2017 | E |
| 1710 | Tinikling 2: The Sequel 2 Help Cleverlyn figure out the minimum number of dance moves her dancers must drop! | 2017 | E |
| 1711 | FlipTop Sort Yo! Yo! Yo! Can Abra sort the stack of papers by only flipping the tops? | 2017 | E |
| 1712 | Lolo Generoso Will the will be fixed? | 2017 | E |
| 1713 | The Ultimate Rescue Rescue Denzel. | 2017 | E |
| 1714 | A Tale of Two Tribes Help the peace talk organizers prevent the media from destabilizing the two tribes. | 2017 | E |
| 1715 | Dick and a Box See if you're wise enough to know how to solve this problem about Dick and a box. | 2017 | E |
| 1741 | Superstitious Sign, seal, and deliver your submission to this problem. | 2017 | F0 |
| 1742 | Fermat's Last Theorem FINAL NA TALAGA Even Fermat needed to go through a few drafts. | 2017 | F0 |
| 1743 | Sharing Chocolates 5: The Umpire Strikes Back Ay kamatis! | 2017 | F0 |
| 1744 | Colored Tile Puzzle Nyeh heh heh. | 2017 | F0 |
| 1751 | Bits by Dr Dre Juju to the bits with this problem involving Dre. | 2017 | F1 |
| 1752 | Betty's Bitter Batter Bother How many ways can Betty put the bitter batter in bowls such that she does not become bothered? | 2017 | F1 |
| 1753 | The Chenes of The Chorva Find the sum of the chenes of all the chorva. | 2017 | F1 |
| 1754 | Bisayaka Grid Bisayaka Grid? | 2017 | F1 |
| 1761 | Krazy Karl Krazy Karl has a krazy way of deciding! | 2017 | F2 |
| 1762 | Gora the Explorer Can you help Gora and Hector manage to bring blue crystals to their friend waiting in Los Pollos Hermanos? | 2017 | F2 |
| 1763 | Kapuluan ng Kalayaan This is a ferry interesting problem. | 2017 | F2 |
| 1764 | Heavy Metal Wall Decoration Can you help the heavy metal fans arrange their heavy metal pipes? | 2017 | F2 |
| 1771 | Guardians of the Lunatics Vol. 2 Prevent the patients from coming a little bit closer to a dangerous wham bam shang-a-lang to their mental health. | 2017 | F3 |
| 1772 | Agadoo A surprising twist unravels as MMORPG players push pineapple by the tree while the fruit sings a hula melody. | 2017 | F3 |
| 1773 | Spreadsheet Game What will the value of the final cell be in this fun spreadsheet game? | 2017 | F3 |
| 1774 | Constructing a City Plan Persevere! I know you can manage this city problem! | 2017 | F3 |
| 1775 | Lito Lapida's Lost Lapida Lito's tombstone was stolen by heartless thieves! It seems he was right in saying: saging lang ang may puso. | 2017 | F3 |
| 1801 | Dubidubidapdap Bee-beep beep beep beep beep beep beep beep! | 2018 | E |
| 1802 | Congratulations Bimb! Help Mommy Kris make a tarp of Bimb's best grades. | 2018 | E |
| 1803 | Palacañang Portrait During his European tour, President Palaka takes a picture at Frague. | 2018 | E |
| 1804 | He Attac But Also Protec Get you a Bato that can do both. | 2018 | E |
| 1805 | Extreme Ambulation The intent is to provide players with a sense of pride and accomplishment. | 2018 | E |
| 1806 | Lodi Petmalu Werpa! | 2018 | E |
| 1807 | Tsunderefs Help the kitchen appliances get as far away from each other as possible. | 2018 | E |
| 1808 | Ika-6 na Ordinansa It comes after the ika-5 na ordinansa, and before the ika-7 na ordinansa. | 2018 | E |
| 1809 | Number Party Can I get your number? | 2018 | E |
| 1810 | Help Your Friend Come Out It is terrifying to come out of closets. Can you help your friend come out? | 2018 | E |
| 1811 | Cooking by the Book You know you can't be lazy! The cake will end up crazy! | 2018 | E |
| 1812 | Robin vs The Penguin The most ambitious crossover event in NOI.PH history. | 2018 | E |
| 1813 | Keribells and Keriboomboom Can you solve this problem? Kering-keri yan! | 2018 | E |
| 1814 | Pakain ng Pahiyas Keeping the traditions of the Pahiyas Festival going! | 2018 | E |
| 1815 | Breakdown Budget In which Harry rides the train to show that he understands the everyday plight of commuters. | 2018 | E |
| 1841 | Studying Diplomacy Spy on text messages! What a relevant application of technology. | 2018 | F0 |
| 1842 | The Speedup Loop Making a program run faster is as easy as removing a single character. | 2018 | F0 |
| 1843 | Yumamma II Yumamma's so smart, she can easily solve this problem. | 2018 | F0 |
| 1844 | Sharing Chocolates 6: Return of the Juday The worse out of the original Sharing Chocolates trilogy. | 2018 | F0 |
| 1851 | Voltes Group The superelectromagnetic robots get stuck together. | 2018 | F1 |
| 1852 | Global Warming Not a real problem. | 2018 | F1 |
| 1853 | Thrust Trials Help Vanilla and Spwet's engineers in their top-secret spaceship project. | 2018 | F1 |
| 1854 | Lean on Me What do you call flying planks? Plywood. | 2018 | F1 |
| 1855 | Boomerang Gadget My only healing is that you switch this gadget into healing mode. | 2018 | F1 |
| 1861 | Merging and Missiles The robots use their superelectromagnetism to stick alien ships together. | 2018 | F2 |
| 1862 | Sister Spaceships Vehicles that transform. Definitely not something I've heard before. | 2018 | F2 |
| 1863 | Late-Night Littering Will The Cleaner Alien catch The Illegal Alien? | 2018 | F2 |
| 1864 | Backbreaking Breakout President Froggy is trapped in jail! Help him escape! I mean, if you want to. | 2018 | F2 |
| 1865 | People Power Rally in EDSA! Make a stand! Get people frustrated! Then find the sum of the frustrations of a subarray of the rallyists! | 2018 | F2 |
| 1871 | Parañaqueue Parañaqueue, queue, queue, push pineapple, shake the tree. | 2018 | F3 |
| 1872 | Mood Swings Arrange songs in a radio station to maximize profit, because we're all greedy capitalists. | 2018 | F3 |
| 1873 | Socrates and Plateau Maybe if you ask the right questions, you'll learn the method to solving this problem. | 2018 | F3 |
| 1874 | Mga Anak ng Tokwa These reproductive tofu have a strange family tree... | 2018 | F3 |
| 1875 | Sugar Roll Yema one and only. | 2018 | F3 |
| 1876 | We Are Number One Here's a little lesson in trickery. This is going down in history. | 2018 | F3 |
| 1901 | Next Generation Currency The solution to coins that look the same? Make everyone wear high-tech glasses. | 2019 | E |
| 1902 | Anion Find In Tagalog, "what is that" translates to "anion". | 2019 | E |
| 1903 | Evening Gown "Fortunately, Catriona is fireproof, immune to lava, and can walk on liquids." | 2019 | E |
| 1904 | Aswang Immortal - Trivia! Answer interesting questions about Filipino mythology! | 2019 | E |
| 1905 | Exchange Gift Will Barbie and Jak's exchange gift proceed this Christmas? | 2019 | E |
| 1906 | Lots of Cookies Get those cookies, get those cookies, get those cookies... | 2019 | E |
| 1907 | Dagohoy Rock Lapu-Lapu Boogie The Sugbo-anons and the Bol-anons have agreed to do a dance number together. | 2019 | E |
| 1908 | 最終審判 お前はもう裁かれる。 | 2019 | E |
| 1909 | Spratly Islands Tour Tour the other countries around the Spratly Islands for fishin—no. Minin—uh. Gas explorati—research. Just research. | 2019 | E |
| 1910 | Skyscaping Go on and try to tear me down, I will be rising from the ground. | 2019 | E |
| 1911 | Super Rangers We've never had a problem on merging robots before. Nope. Not at all. | 2019 | E |
| 1912 | ReMotion How do I make a story? Let me count the ways... | 2019 | E |
| 1913 | Yet Another Packing Problem Although Miguel used to specialize at packing sopas, he got a promotion and is now packing pasta. | 2019 | E |
| 1914 | Almost Original We didn't write a story for this problem. Not even a witty joke. You won't get one here either. | 2019 | E |
| 1941 | Sharing Chocolates 7: The Force Equals Mass Times Acceleration The mass times acceleration awakens. | 2019 | F0 |
| 1942 | Totally Not Robots You are a REGULAR HUMAN BEING. Extract sentences from your UTTERANCE QUEUE. | 2019 | F0 |
| 1943 | Mystery Function Does every finite group appear as the Galois group of some Galois extension of the rationals, and not just cyclic groups? | 2019 | F0 |
| 1944 | City Map Make a spicy city map for your friends' parties. | 2019 | F0 |
| 1945 | Bato Bato Split Pick and split! | 2019 | F0 |
| 1951 | Magkaribal sa Arnibal "When the MRT arrives, each person simultaneously throws their taho." | 2019 | F1 |
| 1952 | Baby Come Bak Bring your baby back to bakuna. | 2019 | F1 |
| 1953 | Tower Bloxx Stack the tower blocks in the right order. | 2019 | F1 |
| 1954 | The Room Do you know what a downdog is? It's the opposite of an upcat. | 2019 | F1 |
| 1955 | Sumbong Centers Help construct Sumbong Centers in Siyudad City. | 2019 | F1 |
| 1961 | Illegal Logging Are you familiar with what Filipinos say about illegal logging? | 2019 | F2 |
| 1962 | BATIBots The Brainy Automated Transcendental Intelligent Bots guard Mactan from colonizers. | 2019 | F2 |
| 1963 | Mr. Kupido Help Mr. Kupido make a group of people fall in one-sided love. | 2019 | F2 |
| 1964 | Sorting the Planets Follow the example of Kevin, the cosmic maintainer of the universe. | 2019 | F2 |
| 1965 | Cartogram Can you make a map by following following following these instructions? | 2019 | F2 |
Legend:
- S Sample problem. Created only for a series of tutorial posts (this and this).
- PR Practice problems released before the Elimination Round. (Only for 2014)
- Tx Training problems released one week before each Elimination Round x. (Only for 2015)
- Ex Elimination Round problem. x signifies which round. If there is only one round, x is omitted.
- Fx Final Round problem. x signifies which round. If x = 0, then it was during the finals practice round.