So, about those plagiarism flags on 2170F...

Look, I’m going to address the elephant in the room.

If you’ve seen my recent submission [351054331] for problem 2170F, or if you’ve seen the downvotes on my recent comments, you know the situation. I’ve been flagged for plagiarism. My code looks suspiciously similar to a huge "cluster" of other submissions.

I get it. Honestly, I do.

If I were a judge or a regular user scrolling through the standings, and I saw 50 people submit nearly identical code, my first thought would be: "Okay, clearly someone leaked the solution on Telegram." It looks bad. It looks guilty.

But here is the incredibly frustrating reality: I didn't copy a single line. And I want to explain why my code looks like everyone else's, not as an excuse, but as a developer.

The "Hello World" Effect

Imagine I asked 100 C++ programmers to write a "Hello World" program. They would all write: #include <iostream> int main() { cout << "Hello World"; }

If 100 people submitted that, would you ban them all for plagiarism? Of course not. There is essentially only one optimal way to write it.

Problem 2170F is the "Hello World" of Offline DP.

This problem forces you into a tiny box. To pass the time limits, you have to use a specific set of tools. Once you pick those tools, the code basically writes itself.

1. The "Backward Loop" that got me flagged

People are pointing out that my inner loop iterates backwards (k--). They say this is the "signature" of the leaked solution.

Guys, come on. It’s a Knapsack-style DP. Iterating backwards is literally Rule #1 of 1D Knapsack optimization so you don't reuse the same item twice. I didn't write it that way because I was copying a cheat sheet; I wrote it that way because if I iterated forwards, the code would be wrong.

I am essentially being punished for knowing how to write a correct Knapsack loop.

2. The "Boilerplate" Trap

The problem requires handling queries offline. So, naturally, I made a vector of queries and iterated from 1 to N. Is that copying? No, that’s just... how you solve offline query problems. That’s the standard template.

Caught in the Crossfire

I think the reason I'm getting downvoted isn't because people genuinely analyzed my code and found proof of cheating. It's because the community is tired.

We are all sick of cheaters. We are sick of contests being ruined by leaked solutions. So when a massive wave of cheaters comes in, the "innocent until proven guilty" mindset goes out the window. It becomes a witch hunt. The system sees a pattern, and it nukes everyone matching that pattern.

I just happened to write the optimal, standard solution at the same time a bunch of copy-pasters did.

The Bottom Line

It sucks to grind on a problem, figure out the optimization (the "Rightmost Index" trick), debug it, submit it, and then get slapped with a plagiarism tag just because the solution is standard.

I’m not asking for special treatment. I’m just asking you to look at the context. Sometimes, "great minds think alike" isn't just a saying—in competitive programming, it’s often the only way to get AC.

I didn't cheat. I just solved the problem.

Thanks for hearing me out.

Appeal Regarding Plagiarism Flag: Submission [351054331]

To the Administration/Judge,

I am writing to formally appeal the plagiarism flag on my submission [351054331] for problem 2170F. While I acknowledge that my solution coincides with a list of other users, I want to state clearly and unequivocally that I wrote this code independently.

The reason so many people (including myself) wrote nearly identical code is that this problem requires a very specific, standard optimization technique known as "Offline Queries with Rightmost Index DP."

Here is a detailed breakdown of exactly why my code ended up looking like others:

1. The "Offline Query" Boilerplate

Since the problem asks about ranges, the standard, most efficient method is to process the queries "offline." This involves iterating through the array once (from index $$$1$$$ to $$$N$$$) and handling all queries ending at the current index $$$R$$$.

My code does exactly this:

vector qryAt[MAXN]; // ... for (int r = 1; r <= n; r++) { ... }

This is not unique logic; it is the standard boilerplate for offline processing. Almost every C++ competitive programmer uses a vector of structs or pairs to store the queries in this manner.

2. The "Rightmost Index" Trick

The core difficulty of this problem is checking if a subset exists within the range $$$[L, R]$$$. The textbook trick for this is to avoid storing a boolean and instead store the rightmost index.

The logic is defined as follows: * $$$dp[k][x]$$$ = the largest index $$$i$$$ such that we can form XOR sum $$$x$$$ using $$$k$$$ elements ending at $$$i$$$.

The validation check then becomes standard: If $$$dp[k][target] \ge L$$$, then the subset is valid.

Once you know this trick, there is essentially only one way to write the if statement. It is not copied; it is a direct implementation of the required logic.

3. The Loop Structure (Knapsack Style)

You will notice my inner loop iterates backwards:

for (int k = 12; k >= 2; k--) { ... }

I wrote it this way because it functions exactly like the 1D Knapsack DP. You must iterate backwards to ensure you do not use the current element $$$a[r]$$$ more than once for the same subset size. This is not a stylistic choice—if I had looped forwards, the logic would be incorrect.

4. Constants and Variables

• 4096 and 13: These are not random numbers. The problem constraints limit values to 4096 and the subset size to 12. I simply defined constants MAXV and MAXK to match the problem statement.
• Variable Names: n, q, l, r, x are simply the variable names provided in the input section of the problem statement.

Conclusion

When a problem has tight constraints and relies on a specific "textbook" optimization (Rightmost Index DP), the solution space is extremely small. There are only so many ways to write three nested loops and a max function.

The similarity is due to "convergent evolution" on a standard algorithm, not plagiarism. I request that you review the code with this context in mind.

I am writing this to address the plagiarism flag regarding my submission [351044555] for problem 2170E. I understand that my code shares significant similarities with several other users. However, I want to clarify that this code was written independently.

The "coincidence" is a result of the problem requiring a highly specific, standard mathematical approach (Linear DP with Prefix Sum optimization) which leaves very little room for implementation variation. Below are the specific points explaining why this convergence occurred naturally.

1. Standard Mathematical Recurrence

The problem reduces to finding the number of valid binary strings where the last block satisfies specific constraints. The recurrence relation is standard for this type of problem:

To solve this in $$$O(N)$$$ (which is required given $$$N \le 3 \cdot 10^5$$$), one must use prefix sums. My code calculates:

cur = pref[i-1] - pref[L-1]

This is the direct translation of the math formula. Any optimal solution must write this exact line of logic. There is no other efficient way to express this.

2. Constraint Propagation Logic

The way I handled the input constraints is the standard "Right-endpoint maximization" technique:

cpp
lim[r] = max(lim[r], l); // Store tightest constraint ending at r
// ... later ...
lim[i] = max(lim[i], lim[i-1]); // Propagate the constraint forward

This isn't unique code; it’s a textbook pattern in Competitive Programming for handling ranges. Most people who know DP would implement it exactly like this because max is the cleanest way to do it.3. My variable names are genericA huge part of the similarity comes from my variable names:dp and pref: Everyone uses these for DP and Prefix Sums.lim: Short for limit.n, m, l, r: These are just the variable names from the problem statement.If I had named them arr1 or x, the code wouldn't look similar, but I used the standard names that everyone uses to keep track of logic.4. The solution is extremely shortThe actual logic is only about 10-15 lines long.The templates (bits/stdc++.h, ios::sync...) are standard.The base case dp[0] = 2 is just a mathematical necessity.When a code snippet is this short and follows a strict formula, the "randomness" is very low. It is highly probable for two people to write identical for loops and modulo operations just by coincidence because there is no other logical way to write them.ConclusionMy code matches others not because of a leak, but because we all wrote the standard $$$O(N)$$$ solution using the standard CP conventions. I’m happy to discuss the logic further if needed, but I hope you can see this is just a case of "convergent evolution" on a standard problem.