SKILL.md
XCPC: jiangly C++ Style
Overview
Proven C++ coding style from jiangly's Codeforces submissions. Focuses on safety, maintainability, and modern C++ features for competitive programming.
Core principle: Zero global pollution, zero global arrays, explicit types, modern C++.
When to Use
- Writing C++ solutions for Codeforces, ICPC, AtCoder, etc.
- Creating competitive programming templates
- Reviewing contest solutions
- Teaching competitive programming best practices
Don't use for:
- Production C++ code (different requirements)
- Non-competitive programming projects
Quick Reference
| Category | Rule | File |
|---|---|---|
| Namespace | Never using namespace std; |
[no-global-namespace](rules/no-global-namespace.md) |
| Arrays | Zero global arrays | [zero-global-arrays](rules/zero-global-arrays.md) |
| Types | Use using i64 = long long; |
[explicit-types](rules/explicit-types.md) |
| Indexing | Follow problem's natural indexing | [keep-indexing-consistent](rules/keep-indexing-consistent.md) |
| I/O | Disable sync, use \n |
[fast-io](rules/fast-io.md) |
| Naming | snake_case for vars, PascalCase for structs |
[naming](rules/naming.md) |
| Formatting | 4-space indent, K&R braces, no line compression | [formatting](rules/formatting.md) |
| Simplicity | Prefer simple data structures | [simplicity-first](rules/simplicity-first.md) |
| Memory | Use in-place operations | [in-place-operations](rules/in-place-operations.md) |
| DFS | Use depth array, avoid parent parameter | [dfs-techniques](rules/dfs-techniques.md) |
| Recursion | Lambda + self pattern | [recursion](rules/recursion.md) |
| Structs | Constructor patterns, const correctness | [struct-patterns](rules/struct-patterns.md) |
| Operators | Overload patterns for custom types | [operator-overloading](rules/operator-overloading.md) |
| Helpers | chmax, ceilDiv, gcd, power, etc. | [helper-functions](rules/helper-functions.md) |
| DP | Use vector, never memset |
[dp-patterns](rules/dp-patterns.md) |
| Modern C++ | CTAD, structured binding, C++20 features | [modern-cpp-features](rules/modern-cpp-features.md) |
Code Template
#include <bits/stdc++.h>
using i64 = long long;
void solve() {
int n;
std::cin >> n;
std::vector<int> a(n);
for (int i = 0; i < n; i++) {
std::cin >> a[i];
}
std::cout << ans << "\n";
}
int main() {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
int t;
std::cin >> t;
while (t--) {
solve();
}
return 0;
}Red Flags - STOP
| Anti-pattern | Correct approach |
|---|---|
using namespace std; |
Use std:: prefix |
int a[100005]; global |
std::vector<int> a(n); in solve() |
#define int long long |
using i64 = long long; |
for (int i = 1; i <= n; i++) |
for (int i = 0; i < n; i++) OR keep problem's indexing |
void dfs(int u, int p) global |
Lambda with self capture |
std::endl |
Use "\n" |
if (x) do_something(); |
Always use braces |
| Over-engineered HLD + segment tree | Use binary lifting for simple path queries |
Creating e1, e2 containers |
Use vis boolean array |
| Converting 1-indexed to 0-indexed | Keep original indexing |
| Passing parent in DFS | Use depth array to check visited |
| Explicit template parameters | Use CTAD where possible |
Full Documentation
For complete details on all rules: [AGENTS.md](AGENTS.md)