| 601 | Cpal | Din Folclor | Infoarena Monthly 2012, Runda 7 | N/A |
| 602 | Craciun | Tamio-Vesa Nakajima | Algoritmiada 2018 Runda Maraton | N/A |
| 603 | Crescator | Paul-Dan Baltescu | Selectie Girls Programming Camp | N/A |
| 604 | Crescator 3 | Marius Nicoli | PreOJI 2017 | N/A |
| 605 | Crescator2 | Tudose Vlad Andrei | Urmasii lui Moisil 2016, Clasele 11-12 | N/A |
| 606 | Cri | Carmen Minca | OJI 2011, clasa a 9-a | N/A |
| 607 | Criptare | Mircea Bogdan Pasoi | .campion 2006-2007, Runda 4 |      4/5 |
| 608 | Criptare2 | Dragos Alin Rotaru, Mihai Nitu | FMI No Stress 5 | N/A |
| 609 | Cristale | Vlad Stoian | Concursul National Urmasii lui Moisil 2012, Clasa a 9-a |      2/5 |
| 610 | Critice | Silviu-Ionut Ganceanu | preONI 2005 Runda 3 |      4/5 |
| 611 | Critice2 | Mihai Calancea | Algoritmiada 2013, Runda 1 | N/A |
| 612 | Criza | Antoneta Lazarescu, Gabriela Coaja | CCEX 2009 | N/A |
| 613 | Croco | Dan-Ionut Fechete | .campion 2006 | N/A |
| 614 | Cruce | Florian Marcu, Ionut Bogdanescu | FMI No Stress 3 | N/A |
| 615 | Csir | Mugurel Ionut Andreica | ONI 2005 |      5/5 |
| 616 | Cstring | Cosmin Silvestru Negruseri | Lot Resița 2012 - Baraj 1 Seniori | N/A |
| 617 | CT | Mugurel Ionut Andreica | Happy Coding 2006 |      4/5 |
| 618 | Cu calu' la JBOI | Costin Oncescu | Junior Challenge 2015 | N/A |
| 619 | Cu mâinile curate | Andrei Constantinescu | Junior Challenge 2015 | N/A |
| 620 | Cuantictiori | Cezar Trisca-Vicol | Autumn WarmUp 2020 | N/A |
| 621 | Cub | Alin Burta | ONI 2006, clasa 10 | N/A |
| 622 | Cub2 | Claudiu-Cristian Gorea | ONI 2015, clasa a 9-a | N/A |
| 623 | Cub5 | Gheorghe Manolache | ONI 2019, clasa a 9-a, ziua 2 | N/A |
| 624 | Cuba | Chichirim George | Concursul National de Informatica "Adolescent Grigore Moisil" 18 | N/A |
| 625 | Cubeon | Tamio-Vesa Nakajima | AGM 2019, runda nationala | N/A |
| 626 | Cuburi | Daniel Pasaila | .campion 2007 |      5/5 |
| 627 | Cuburi2 | Paul-Dan Baltescu | Stelele Informaticii 2009, clasele 9-10 | N/A |
| 628 | Cuburi3 | Clara Ionescu | Grigore Moisil 2009, clasa a 10a | N/A |
| 629 | Cuburi4 | Rodica Pintea | Lot Juniori 2009 - Baraj 1 | N/A |
| 630 | Cuburi5 | Andrei Grigorean | Algoritmiada 2010, Runda 4 | N/A |
| 631 | Cufar | Cristian Toncea | OJI 2018, Clasa a 9-a | N/A |
| 632 | Cufere | Liliana Schiopu | OJI 2023, clasa a 9-a | N/A |
| 633 | Cuiburi | Marius Dumitran | ONI 2010 - Baraj | N/A |
| 634 | Culegere | Stefan Negrus | Urmasii lui Moisil 2016, Clasa a 9-a | N/A |
| 635 | Culmi | Marinel Serban | Lot 2005 Sibiu | N/A |
| 636 | Culoar | Andrei Grigorean | Algoritmiada 2011, Runda 2 | N/A |
| 637 | Culori | Adrian Vladu | preONI 2007, Runda 2 |      3/5 |
| 638 | Culori2 | Radu Berinde, Tiberiu Danet | Lot 2004 | N/A |
| 639 | Culori3 | Carmen Popescu | OJI 2012 - clasa a 10-a | N/A |
| 640 | Culori4 | Mihai Calancea | Infoarena Monthly 2012, Runda 8 | N/A |
| 641 | Cumpanit | Ciprian Chesca | ONI 2013, clasa a 10-a | N/A |
| 642 | Cupa Berii | Marius Dumitran | ONIS 2015, Runda 2 | N/A |
| 643 | Cuplaj maxim de cost minim | Arhiva Educationala | Arhiva Educationala | N/A |
| 644 | Cuplaj maxim in graf bipartit | Arhiva Educationala | Arhiva educationala | N/A |
| 645 | Cuplaje | Eugenie Daniel Posdarascu | Algoritmiada 2016 Runda 3 Seniori | N/A |
| 646 | Curatenie | Dragos Oprica | FMI No Stress 3 |      1/5 |
| 647 | Curcani | Alexandru Luchianov | Summer Challenge 2021 | N/A |
| 648 | Curcubeu | Andrei Grigorean | Autumn Warmup 2007, Runda 2 | N/A |
| 649 | Curent | Dan-Ionut Fechete | ONI 2008, clasele 11-12 | N/A |
| 650 | Curs Valutar | Vlad Duta | ONIS 2014, Runda 4 | N/A |