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, standing on tiptoes will bring you closer to the sun
.
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Summary of question types
| 2021 |
2020 |
2019 |
2018 |
2017 |
2016 |
2015 |
2014 |
2013 |
| Traverse each bit |
enumerate |
DFS |
time and date |
Simple calculation excel |
Simple calculation |
Enum plus string search |
enumerate |
time and date |
| Enumeration + set deduplication + mathematical formula |
greatest common divisor |
Base conversion |
binary conversion |
Judgment of prime numbers, triple violent enumeration |
Arithmetic sequence sum |
Simple calculation |
Thinking, induction, finding rules |
Brute force enumeration |
| Violent enumeration (optimization/set deduplication) |
Mathematics + finding rules |
Recursion |
Mathematics + Thinking + Large Number Conversion |
Pay attention to the measurement unit of the array. To be precise, enlarge it by 2^30 to do the division. |
Full arrangement+check |
Enumeration + judgment, mathematical reasoning to reduce unknowns |
Recursively search for all solutions |
recursion |
| Shortest path (floyd, Deegers + finding the greatest common denominator and least common multiple) |
DFS+ Union Search |
Enumeration + permutation check |
dynamic programming |
dfs |
naked question |
Width and output content |
Addition of large numbers, division of large numbers, Golden Section and Fibonacci |
|
| Computer composition principle basic unit conversion |
time and date |
BFS |
divide and conquer thinking |
Recursively figure out the meaning of parameters and the direction of parameter changes |
Recursion, clarify the meaning of parameters and the direction of change of parameters |
Recursive search for total arrangement |
recursion, holistic thinking |
character processing |
| Dynamic Programming 01 Knapsack Problem |
Convert between strings and numbers |
Simple calculation |
Sort + Divide |
classic dp |
Full arrangement+check |
Enumeration, clever calculation |
Enum + greatest common divisor |
Quick sort + (double pointer) |
| time and date |
String + reverse order + prefix + suffix |
Binary tree |
Mathematics + Thinking |
General date arithmetic, careful, consider leap years; string processing |
DFS cannot solve the T-shaped combination. Full arrangement + DFS finds the connected blocks in the matrix. |
recursion |
Full arrangement |
Sorting + traversal (transformation of strings and integers) |
| Mathematical thinking + binary enumeration |
Simple calculation |
Mathematics+Greatest Common Divisor+Euclidean Algorithm |
Sorting + set deduplication + map |
Extended Euclidean + complete knapsack problem (dp) |
Enumeration + optimization (hash cache) |
Find symbolic formulas with examples |
thinking |
BFS/Law |
| You can use sort to cheat points (correctly it’s mathematical thinking + stack) |
string substring |
Mathematics + Classification Discussion |
BFS |
binary enumeration |
greedy |
Matrix Operations |
memory recursion |
Full arrangement + string cutting; Full arrangement + string to integer conversion |
| dynamic programming |
Mathematics + Thinking |
Mathematics + Thinking + Absolute Value |
sort + odd and even |
Prefix sum + combinatorics |
Mathematics, geometric sequence, preprocessing |
Convert an unrooted tree to the number of roots, dfs, maintain the maximum weight sum that can be obtained when each node is used as the root |
tree array |
Simple enumeration |
From the table above, we can see that the common test points mainly include: date and time issues, enumeration ( but generally we will not take the test alone, but will combine set, map, greatest common divisor, etc.), mathematics + thinking + finding patterns, dynamic programming, characters String, full permutation , greatest common divisor , sorting (binary search, quick sort, divide and conquer idea), DFS, BFS.
In recent years, you will find that the questions of the Blue Bridge Cup have become more and more difficult, less 'violent', and more inclined to dynamic programming and mathematical thinking . This kind of questions is generally not simple, but it doesn't matter. The first few fill-in-the-blank questions are still more biased. The enumeration test must be combined with set deduplication, binary search, map, and other skills tests. You can master it almost by doing a few real questions. The second is the date problem, which is still common . We can use excel and the computer's own You can do it with a calculator. It’s no problem to get three points saved on simple questions.
The second thing is to master some backtracking algorithms. You can read my blog about backtracking algorithms . You really can’t do direct violent search, but you can get some points . There are also full permutations, greatest common divisors and least common multiples, set deduplication, vector, map, etc. STL container, sort, max and other algorithms and other common functions in libraries, string and integer switching, large number multiplication and other techniques and templates should be remembered more. It is very common in competitions. This is basically stable and economical. Finally, there are Yu Li’s students can learn the DP algorithm and watch this video. After learning the DP analysis method you can prepare for the national competition.
Not much to say, after knowing this, of course you still need to practice more questions: here are the real questions classified according to the proportion of question types. You can practice if necessary.
Frequently asked questions practice
Frequently asked questions template:
Frequently asked questions template
Frequently asked questions template 2
Past questions
2013 The Fourth C/C++ Real Exam Questions [Provincial Competition] [Group B]
2014 The Fifth C/C++ Real Exam Questions [Provincial Competition] [Group B]
2015 Sixth C/C++ Real Exam Questions [Provincial Competition] [Group B]
2016 The 7th C/C++ Real Exam Questions [Provincial Competition] [Group B]
2017 The 8th C/C++ Real Exam Questions [Provincial Competition] [Group B]
2018 Ninth C/C++ Real Exam Questions [Provincial Competition] [Group B]
2019 The 10th C/C++ Real Exam Questions [Provincial Competition] [Group B]
2020 Eleventh C/C++ Real Exam Questions [Provincial Competition] [Group B]
2021 The 12th C/C++ Real Exam Questions [Provincial Competition] [Group B]
Official website for brushing questions: brushing real questions
Video explanation
2013-2017 Lanqiao Cup real test questions explanation: 2013-2017 real test questions explanation
2018-2021 Lanqiao Cup real test questions explanation: 2018-2021 real test questions explanation
Algorithm explanation: Algorithm explanation
game skills
1. First of all, you can use office software and calculators in the competition. You can make full use of questions like finding patterns, finding mazes, and finding dates.
2. Use the STL library in C++ more. After all, it is an API built by a master. It is definitely more efficient than writing it yourself, and it can help you solve problems faster, such as the sort and qsort functions, and it is less error-prone.
3. It is necessary to master some fixed templates and a skill, such as: full arrangement, violent search to score points, conversion of strings and integers, multiplication of large numbers, etc.
4. Do more simulations before the exam. I recommend the official website of Lanqiao Cup and ACWing.
Finally, I wish you all good results in the exam
——A confident life is the most beautiful!