solve-skeleton

Solve Skeleton Skill

Bare-bones Python solve() skeletons for ACM/OJ problems. No logic inside — only structure, I/O plumbing, and TODO markers. After filling TODOs, use the algo-annotation skill to add Chinese comments and # [防错] markers.

1. Core Convention

I/O

input = sys.stdin.readline
n = int(input())
nums = list(map(int, input().split()))

For strings: s = input().strip(). For output: print(ans) or print("\n".join(out)). Never use sys.stdin.buffer, iter(data) + next(it), or .buffer.read().split().

Stage Separator

Five dashes, 58 equal signs. No trailing content.

# ============================================================

5-Phase Structure

Every solve() follows this layout:

def solve():
    """Input format: ...
    Output format: ...
    """
    input = sys.stdin.readline

    # ============================================================
    # Preprocess
    # ============================================================

    # ============================================================
    # Algorithm
    # ============================================================

    # ============================================================
    # Output
    # ============================================================

if __name__ == "__main__":
    solve()

The docstring must state input and output format — this is the contract with the grader.

2. Anti-Pattern Checklist

Never do these when writing a skeleton. They cause WA/TLE that are hard to debug.

• No sys.stdin.buffer — returns bytes, requires .decode(), breaks on mixed string/numeric input.
• No input() without alias — bare input() is slow on large data; always input = sys.stdin.readline.
• No list.pop(0) in BFS — use deque.popleft() or you get O(n²) per pop.
• No recursive find() in DSU — Python recursion limit (~1000) causes RecursionError on deep chains. Use iterative find with path compression.
• No missing 0-based conversion — if input is 1-based, subtract 1 immediately after reading.
• No .strip() omission on string reads — input().strip() removes trailing \n; input() includes it.
• No forgetting if __name__ == "__main__" — some OJ platforms require the guard.
• No stale heap entries in Dijkstra — always skip with if d != dist[u]: continue.