Programming competitions and contests, programming community. Problemsetters no longer know what most of those categories are. Strongly Connected Components(SCC) http://codeforces.com/problemset/problem/427/C. http://www.spoj.com/problems/PHT/ (2) //easy BS (NN+2N) mby math? Max-Clique, 7743 — Cliques (Similar to ADAPARTI) (8) //Parametrisation, 7616 Counting Cliques (4) //[NICE][CLIQUES][ELIMINATING-SETS], https://codeforces.com/contest/1181/problem/A (2) //[EASY][FORMULA][MODULO], https://www.spoj.com/problems/PRADIPSUM/ (2) //[EASY][FORMULA], http://codeforces.com/contest/729/problem/B 2, http://codeforces.com/contest/710/problem/C 4, http://www.spoj.com/problems/JOCHEF/ (5) //NICE: Lagers rectange 0/1 O(N*M), http://www.spoj.com/problems/ADAGCD/ [+STL], https://codeforces.com/contest/1175/problem/A (2) //[EASY][SYMPATHIC][DIVISION], https://codeforces.com/contest/1203/problem/C (3) //[NICE][GCD], https://devskill.com/CodingProblems/ViewProblem/553 (3) //[VERY NICE][SIMPLE], https://devskill.com/CodingProblems/ViewProblem/560 (2), https://codeforces.com/contest/1176/problem/B (2) //[MODULO][GREEDY], https://codeforces.com/contest/1200/problem/C (4) //[VERY NICE][GCD][LCM], https://codeforces.com/contest/1182/problem/A (2) //[EASY][DP], https://atcoder.jp/contests/abc136/tasks/abc136_b (2) //[IMPLEMENTATION][CONVERSION], https://codeforces.com/contest/1185/problem/A (1), https://codeforces.com/contest/1198/problem/F (6) //[VERY NICE][RANDOM][FACTORISATION][PRIME][GCD], https://codeforces.com/contest/1183/problem/B (2) //[EASY][FORMULA][MIN/MAX], https://codeforces.com/contest/1187/problem/A (1) //[EASY][FORMULA], https://codeforces.com/contest/1195/problem/B (2) //[EASY][GAUSS][BRUTE], https://codeforces.com/contest/1189/problem/E (5) //[INVERSION][STL], https://www.spoj.com/problems/CANPR/ (5) //[NICE][MOBIUS] Weird TC (weak? -Morass- Can You say the total numbers (digit) :p of the problem listed here :D :D, Hey Anyone Help me with STL very first problem [ADABASET]-(https://www.spoj.com/problems/ADABASET/en/). Are the numbers in the parenthesis your judgement of how difficult each problem is? What's all that? 3) 3 … Can you please share a hint or your code about this one? I'm not mathematician and it seems slightly like magic to me :'( I find it hard somehow :/. Some solved problems of codeforces, atcoder, lightoj and spoj. You Can sort the problems in decreasing order (The most solved first) Problemset - Codeforces http://codeforces.com/contest/31/problem/D (4) //[NICE] Brute-force by recursion, http://codeforces.com/contest/36/problem/B (2) //[NICE][SIMPLE], https://www.spoj.com/problems/MOZPWS/ (4) //[NICE][IMPLEMENTATION][MQ], https://codeforces.com/gym/101972/problem/G (4) //[NICE][SWEEP WORKS TOO], http://codeforces.com/problemset/problem/514/D //+BS, http://codeforces.com/problemset/problem/872/B, https://devskill.com/CodingProblems/ViewProblem/19, http://codeforces.com/contest/713/problem/D 6, http://codeforces.com/contest/675/problem/E 5, http://www.spoj.com/problems/POSTERIN/ 5 //VERY NICE — Delete all minimas, http://www.spoj.com/problems/RPLN/ (3) //RMQ only, http://www.spoj.com/problems/CITY2/ (4) //RMQ + MAP [NICE][VAGUE STATEMENT], http://www.spoj.com/problems/DIFERENC/ (4) //Solve separately (linear D&C), http://codeforces.com/contest/863/problem/E (4) //OR some Queue / sorting, http://codeforces.com/contest/5/problem/C (4) //NICE — many other options, http://codeforces.com/contest/15/problem/D (5) //VERY NICE 2D RM [sliding-windw][monotone-queue], http://codeforces.com/contest/873/problem/E (5) //[NICE][Brute-Force + RMQ], http://www.spoj.com/problems/AROPE2/ 5 //same as above (+time), http://www.spoj.com/problems/ADAPANEL/ [combinatorics], 13301 — Impossible Communication (4) //[CUTE][SAMPLE][OBSERVATION][EASY], http://codeforces.com/problemset/problem/427/C proposed by unofficial10, http://codeforces.com/contest/894/problem/E (5) //[NICE][DP], https://devskill.com/CodingProblems/ViewProblem/79, http://www.spoj.com/problems/TFRIENDS/ (4) //just scc size, http://www.spoj.com/problems/CAPCITY/ (4) //scc destination [WEAK TC], http://codeforces.com/contest/22/problem/E (5) //[NICE][make it strongly connected][SRC>DST], http://www.spoj.com/problems/ADABERRY/ [+TREAP], https://codeforces.com/contest/1180/problem/E (6) //[VERY NICE], https://codeforces.com/contest/1187/problem/D (5) //[VERY NICE][GREEDY][STACK], https://toph.co/p/maintain-the-queue (5) //[NICE][QUEUE], http://codeforces.com/gym/101992/problem/L (5) //[VERY NICE], http://codeforces.com/gym/101982 F //[SWEEP][NORMALIZE][NICE][XOR], http://codeforces.com/gym/101962/problem/I (4) //[BS], http://codeforces.com/gym/101801 G //Two ST [SEQUENCE], http://codeforces.com/gym/101879/problem/G (5) //Merge / Special, http://codeforces.com/gym/101741/problem/J (6) //[NICE][COMBINATORICS], http://codeforces.com/contest/914/problem/D (5) //[NICE][GCD][LOG], http://codeforces.com/contest/915/problem/E (5) //[VERY NICE][UNLIMITED], http://codeforces.com/contest/145/problem/E (5) //[NICE]//Bit swap + subsequence, http://codeforces.com/contest/911/problem/G (7) //Segment tree over queries, http://codeforces.com/contest/895/problem/E (5) //[PRECISION], http://codeforces.com/contest/52/problem/C (4) //Easy [MIN]+[INCREASE], http://codeforces.com/contest/56/problem/E (5) //[NICE][NORMALIZE][MAX], http://codeforces.com/contest/877/problem/E (5) //[VERY NICE][EULER TOUR TREE], https://devskill.com/CodingProblems/ViewProblem/283, https://devskill.com/CodingProblems/ViewProblem/315, http://codeforces.com/problemset/problem/756/C, http://codeforces.com/contest/739/problem/C (8), http://codeforces.com/contest/718/problem/C (8), http://codeforces.com/contest/750/problem/E (7), http://codeforces.com/contest/759/problem/C (7), http://codeforces.com/contest/763/problem/E (8) //VERY NICE — [non-trivial], http://www.spoj.com/problems/BGSHOOT/ (5) //normalize — then easy, http://codeforces.com/contest/765/problem/F (7) //VERY NICE — CASCADE, http://www.spoj.com/problems/GSS1/ (5) //Idea — then easy, http://www.spoj.com/problems/KQUERYO/ (5) //Seg-tree of vectors, http://codeforces.com/contest/633/problem/G (8) //EulerTree+Seg+Bitset, http://www.spoj.com/problems/NAJ0001/ (7) //10^8 int — memory (and worked), http://www.spoj.com/problems/PRMQUER/ (5) //2 segment trees + sieve, http://www.spoj.com/problems/EC_DIVS/ (5) //dunno if intended, http://www.spoj.com/problems/DCEPC11I/ (5) //NICE — 1,2,3,4,5,.. inc, http://www.spoj.com/problems/QUE2/ (4) //kth number, http://codeforces.com/contest/785/problem/E (6) //Seg+Treap [and faster], http://codeforces.com/contest/786/problem/B (6) //+Dijkstra, http://codeforces.com/contest/121/problem/E (7) //Dunno — done by vectorisation, http://codeforces.com/contest/803/problem/G (5) //VERY NICE!! [ld], http://codeforces.com/contest/18/problem/A (2) //EASY&FINE: Pythagoreas, http://codeforces.com/contest/40/problem/A (2) //[EASY][DISTANCE], https://codeforces.com/contest/1182/problem/D (5) //[CENTRUM][OBSERVATION][DFS], https://www.urionlinejudge.com.br/judge/en/problems/view/1562 (5) //[VERY NICE][QUEUE][GREEDY], https://codeforces.com/gym/102001/problem/G (4) //[NICE][BS], https://codeforces.com/gym/102006/problem/G (4) //[NICE][TOPOSORT][OBSERVATION], https://codeforces.com/gym/102058/problem/B (6) //[VERY NICE][REVERSE-SIMULATION], http://codeforces.com/gym/101666 H //[VERY NICE][GEOMETRY][DSU][EULER][PLANAR], http://codeforces.com/contest/27/problem/D (5), http://www.spoj.com/problems/VFRIEND2/ (5) //Graph possible check, http://codeforces.com/contest/859/problem/E (4) //VERY NICE (2 cases: CYCLE [x2] / TREE [x(Size+1)], http://codeforces.com/contest/847/problem/C (2) //Forest making Easy&Nice, http://codeforces.com/contest/863/problem/C (3) //Cycle in states, https://codeforces.com/contest/1175/problem/D (4) //[NICE][PREPROCESS][SORTING], https://codeforces.com/contest/1203/problem/F1 (5) //[VERY NICE][SORTING][CASES], https://codeforces.com/contest/1176/problem/C (3) //[SIMPLE][NICE][IMPLE], https://codeforces.com/contest/1176/problem/A (1), https://codeforces.com/contest/1200/problem/B (3) //[SIMPLE][NICE], https://codeforces.com/contest/1202/problem/A (2), https://codeforces.com/contest/1181/problem/B (4) //[BIG], https://atcoder.jp/contests/abc136/tasks/abc136_c (3) //[REVERSE], https://codeforces.com/contest/1185/problem/C2 (4), https://codeforces.com/contest/1185/problem/B (2) //[EASY], https://codeforces.com/contest/1180/problem/B (3) //[IMPLEMENTATION][MATH], https://codeforces.com/contest/1186/problem/D (4) //[IMPLEMENTATION], https://codeforces.com/contest/1197/problem/B (3) //[BITONIC][IMPLE], https://www.spoj.com/problems/DIVSTR/ (3) //[CUTE], https://codeforces.com/gym/101981 E //[NICE][NORMALIZE][STACK], https://codeforces.com/gym/102001/problem/L (3) //[BITS], http://codeforces.com/gym/100112 (3) //[FINE], http://codeforces.com/gym/101666 (4) //[NICE][QUEUE][DFS][EVENTS], http://codeforces.com/gym/101806/problem/T (5) //[NICE][SEGMENT TREE][SORTING], http://codeforces.com/contest/916/problem/B (3) //[BITS] FIRST & LAST, http://codeforces.com/contest/913/problem/C (3) //+[DP], http://codeforces.com/contest/146/problem/D (4) //[NICE][CONSTRUCTION], http://codeforces.com/contest/146/problem/C (3) //[EASY][NICE][TWO-CASES], http://codeforces.com/contest/139/problem/D (4) //Muchas cases, 7887 — Back to the Future (4) //[NICE][2*HEAP], http://codeforces.com/contest/910/problem/A (2) //DP works too, http://codeforces.com/contest/125/problem/D (4) //Limited possibilities, http://codeforces.com/contest/902/problem/A (2) //Just keep last, http://codeforces.com/contest/898/problem/D (4) //[NICE][FENWICK/OR/PREFIX], http://codeforces.com/contest/118/problem/C (4) //[NICE] — Try each digit (iterate in waves), 7706 — Pokemons (2) //Sweep and keep maximum, http://codeforces.com/contest/893/problem/D (4) //[NICE][SWEEP][MAXIMUM] — pay max when have to, http://codeforces.com/contest/892/problem/B (2) //Sweep from back, http://codeforces.com/contest/102/problem/C (3) //sort by frequency, https://devskill.com/CodingProblems/ViewProblem/419 (2) //Sweep from back, http://codeforces.com/contest/890/problem/C (3) //frequence, http://codeforces.com/contest/890/problem/B (2) //[EASY][REVERSE], http://codeforces.com/contest/888/problem/B (2) //Equalize U/D and L/R, http://codeforces.com/gym/101597/problem/J (4) //[NICE][SWEEP], http://codeforces.com/contest/76/problem/B (4) //[NICE][MATCHING-LIKE][2PTRS], http://codeforces.com/contest/73/problem/B (4) //[IMPLEMENTATION][SORTING], http://codeforces.com/contest/883/problem/K (4) //Nice — Two sweeps, http://codeforces.com/contest/49/problem/D (3) //NICE — 1010101 OR 0101010 [haming], http://codeforces.com/contest/58/problem/C (4) //NICE — group trees by slopes, http://codeforces.com/contest/729/problem/D 3, http://codeforces.com/contest/729/problem/E 4, http://codeforces.com/contest/725/problem/D 4, http://codeforces.com/contest/725/problem/F 9, http://codeforces.com/contest/732/problem/E 5, http://codeforces.com/contest/727/problem/F 6, http://codeforces.com/contest/724/problem/D 5, http://codeforces.com/contest/723/problem/C 4, http://codeforces.com/contest/719/problem/B 2, http://codeforces.com/contest/712/problem/C 3, http://codeforces.com/contest/746/problem/E 5, http://codeforces.com/contest/746/problem/D 3, http://codeforces.com/contest/749/problem/C 3, http://codeforces.com/contest/884/problem/D (4) //PQ or Sort, http://www.spoj.com/problems/SQRMINSUM/ 3 //solve-able in O(N+M)-arrayqueue, http://www.spoj.com/problems/MSCHED/ 3 //sweep from back, http://www.spoj.com/status/ns=18780683 4 //all perm + A