CF 105190E - Hard Test

CF 105190E - Hard Test

Rating: -
Tags: -
Solve time: 31s
Verified: yes

Solution

Problem Understanding

The input contains a single integer n. This value has no effect on the required output. The task is simply to successfully read the integer from standard input and then print the string AC.

The constraint 1 ≤ n ≤ 1000 is irrelevant for the algorithm because the value is never used. Reading one integer and printing one fixed string both take constant time and constant memory.

The only subtle mistake is forgetting to read the input before printing. While many judges ignore unread input for such a simple problem, competitive programming solutions are expected to consume the provided input.

For example, with input

1

the correct output is

AC

Another possible mistake is printing anything other than the exact uppercase string.

For example, with input

1000

printing

ac

or

Accepted

is incorrect because the problem explicitly requires the exact output AC.

Approaches

A straightforward solution reads the integer and prints AC. Since there is only one input value and no computation depending on it, this already solves the entire problem. The running time is constant because exactly one integer is read and one string is printed.

There is no more sophisticated algorithm because the input is intentionally meaningless. The challenge exists only to verify that a contestant can correctly perform basic input and output.

Approach	Time Complexity	Space Complexity	Verdict
Brute Force	O(1)	O(1)	Accepted
Optimal	O(1)	O(1)	Accepted

Algorithm Walkthrough

1. Read the integer n from standard input. The value itself is ignored because it has no influence on the required output.
2. Print the string AC exactly as specified.

Why it works

The problem accepts any input value but always requires the same output. Since the algorithm always prints AC after consuming the input, it matches the specification for every valid test case.

Python Solution

import sys
input = sys.stdin.readline

input()
print("AC")

The program first reads the single input line. The value is discarded because it is never needed. After that, it prints the exact required string. No parsing or additional computation is necessary, so there are no concerns about boundary conditions, overflow, or off-by-one errors.

Worked Examples

Sample 1

Input:

1

Step	Input read	Output
Read input	1
Print	1	AC

The value is ignored after being read, and the program prints the required verdict.

Sample 2

Input:

1000

Step	Input read	Output
Read input	1000
Print	1000	AC

This example shows that even the largest allowed input produces exactly the same output.

Complexity Analysis

Measure	Complexity	Explanation
Time	O(1)	Reads one input line and prints one output line.
Space	O(1)	Uses only a constant amount of memory.

The solution performs a fixed amount of work regardless of the input value, so it easily satisfies any reasonable time and memory limits.

Test Cases

# helper: run solution on input string, return output string
import sys
import io

def solve():
    input = sys.stdin.readline
    input()
    print("AC")

def run(inp: str) -> str:
    backup_stdin = sys.stdin
    backup_stdout = sys.stdout
    sys.stdin = io.StringIO(inp)
    sys.stdout = io.StringIO()

    solve()

    out = sys.stdout.getvalue()

    sys.stdin = backup_stdin
    sys.stdout = backup_stdout
    return out

# sample-style case
assert run("1\n") == "AC\n", "sample"

# custom cases
assert run("1000\n") == "AC\n", "maximum input"
assert run("500\n") == "AC\n", "middle value"
assert run("999\n") == "AC\n", "large value"
assert run("42\n") == "AC\n", "arbitrary value"

Test input	Expected output	What it validates
1000	AC	Largest allowed input.
500	AC	Typical valid value.
999	AC	Another large valid value.
42	AC	Confirms the input value is ignored.

Edge Cases

Consider the smallest valid input:

1

The algorithm reads the value, ignores it, and prints:

AC

Since the output is independent of the input value, this is correct.

Now consider the largest valid input:

1000

The algorithm again reads the integer and immediately prints:

AC

The value never affects execution, so the largest input is handled exactly the same way as every other valid input.