CF 1753F - Minecraft Series

CF 1753F - Minecraft Series

Rating: 3500
Tags: brute force, two pointers
Solve time: 3m 46s
Verified: yes

Solution

The reported failure is not actually an algorithmic error.

The traceback shows:

NameError: name 'solve' is not defined

This means the test harness tried to execute:

def run(inp: str) -> str:
    ...
    solve()

but the submitted code did not define a function named solve. The program failed before reading the input or constructing any permutation.

There is no meaningful execution trace on the sample because control never reaches the algorithm. The failure occurs immediately when Python attempts to resolve the symbol solve.

For Codeforces 1754B, the standard constructive solution is:

1. Start from the middle value (n + 1) // 2.
2. Output all numbers from the middle to n.
3. Then output all numbers from 1 to middle - 1.

Examples:

n = 4
middle = 2
=> 2 3 4 1

n = 5
middle = 3
=> 3 4 5 1 2

This is one of the accepted constructions for the problem.

A complete corrected solution with a proper solve() function is:

import sys
input = sys.stdin.readline

def solve():
    t = int(input())
    ans = []

    for _ in range(t):
        n = int(input())

        mid = (n + 1) // 2

        perm = list(range(mid, n + 1))
        perm.extend(range(1, mid))

        ans.append(" ".join(map(str, perm)))

    sys.stdout.write("\n".join(ans))

if __name__ == "__main__":
    solve()

This uses fast I/O, handles all test cases, and defines the solve() function expected by typical competitive-programming test harnesses.