CF 102899A - KK 画猪

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Solve time: 45s
Verified: yes

Solution

Problem Understanding

The task is intentionally minimal: the program receives a single token on standard input and must respond with a fixed ASCII drawing of a pig. The input is not a general string-processing problem, because there is no transformation required, no parsing logic, and no computation over structure. Instead, the input acts as a trigger, and the output is always the same multi-line artwork.

From an algorithmic perspective, the “data” here is essentially irrelevant beyond being present. The real requirement is correct reproduction of a predefined text block, including spaces, backslashes, and punctuation that would otherwise be easy to corrupt during output formatting.

The constraint profile is trivial in a competitive programming sense. Even if we assume the most standard limits of 1 second and 256 megabytes, the solution cannot meaningfully approach those limits. The only real risk is implementation error in handling raw strings, especially escaping backslashes in Python and preserving exact whitespace.

Edge cases are not about algorithmic branching but about output fidelity. A few concrete failure modes illustrate this.

If a solution attempts to construct the ASCII art with normal string concatenation without carefully escaping backslashes, lines such as (\____/) or / @__@ \ may lose characters or produce invalid escape sequences. A naive implementation might also accidentally strip trailing spaces when using formatting functions, which would subtly corrupt the drawing even if the logic is correct.

Another failure mode occurs when developers try to “compute” the output based on the input string. Since the input is always just "pig", any unnecessary conditional logic increases the chance of mismatched behavior without adding correctness value.

Approaches

The brute-force interpretation of the task is to read the input string, verify it matches the expected trigger word, and then print the associated ASCII art line by line. This is already sufficient because there is no variation in output. The work done is linear in the size of the output text, which is constant.

A more elaborate brute-force attempt might involve storing the ASCII art as a list of strings and iterating over it to print each line. This is still correct, but it introduces unnecessary structure without changing complexity or behavior. The key observation is that the input does not influence the output beyond validating that we should print it.

The optimal solution collapses everything into a single constant-time decision: ignore input content and directly emit the predefined block. The structure of the problem makes this possible because there is exactly one valid output and no conditional branches based on input variation.

Approach	Time Complexity	Space Complexity	Verdict
Brute Force (parse + condition + line-by-line print)	O(1)	O(1)	Accepted
Optimal (direct print constant string)	O(1)	O(1)	Accepted

Algorithm Walkthrough

Read the input string from standard input, even though its value does not affect the result. This is only to satisfy the input contract of the problem.
Prepare a fixed multiline string representing the pig ASCII art exactly as required by the output specification.
Print the string to standard output without any modification.

The key idea is that no branching is required because the problem defines a single valid output state.

Why it works

The correctness comes from the fact that the problem defines a deterministic mapping from any valid input to a single fixed output. Since all valid inputs are identical in effect, the output function is constant. The algorithm does not need to inspect the input content; it only needs to guarantee faithful reproduction of the required string.

Python Solution

import sys
input = sys.stdin.readline

def solve():
    _ = input().strip()

    art = r"""(\____/)
 / @__@ \
( (oo) )
‘-.~~.-’
 /
 \
 @/
 \_
 (/ /
 \ \)
WW‘----’WW
"""
    sys.stdout.write(art)

if __name__ == "__main__":
    solve()

The implementation reads and discards the input because it is irrelevant beyond triggering output. The ASCII art is stored as a raw multiline string so that backslashes are preserved without needing manual escaping. This avoids common Python pitfalls where sequences like \_ or \ might otherwise be interpreted as escape sequences.

The output is written directly using sys.stdout.write to avoid any accidental formatting or additional newline injection that could occur with print in some environments.

Worked Examples

Sample 1

Input is a single word triggering the output.

Step	Input Read	Action	Output
1	pig	read and discard
2	pig	load ASCII art
3	pig	print art	pig ASCII art

This trace shows that the input content never participates in any decision-making. The output is fully determined before execution begins.

Sample 2

Consider again the same input, since variation is not possible.

Step	Input Read	Action	Output
1	pig	read and discard
2	pig	no conditional logic
3	pig	print identical art	pig ASCII art

This confirms that repeated executions are identical and stateless.

Complexity Analysis

Measure	Complexity	Explanation
Time	O(1)	Only a constant amount of input reading and printing of a fixed string
Space	O(1)	The ASCII art has constant size independent of input

The constraints of the problem are far above what is needed here. Even repeated execution or large system limits are irrelevant because the output size is fixed and small.

Test Cases

import sys, io

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

    import sys
    input = sys.stdin.readline

    def solve():
        _ = input().strip()
        art = r"""(\____/)
 / @__@ \
( (oo) )
‘-.~~.-’
 /
 \
 @/
 \_
 (/ /
 \ \)
WW‘----’WW
"""
        sys.stdout.write(art)

    solve()
    return sys.stdout.getvalue()

# provided sample
assert run("pig\n") == r"""(\____/)
 / @__@ \
( (oo) )
‘-.~~.-’
 /
 \
 @/
 \_
 (/ /
 \ \)
WW‘----’WW
"""

# custom cases
assert run("pig\n") != "", "output must not be empty"
assert run("pig\nextra") == run("pig\n"), "extra input after token ignored in strip-based read"
assert run("pig\n") == run("pig\n"), "idempotence check"

Test input	Expected output	What it validates
pig	ASCII pig	standard case correctness
pig with extra text	ASCII pig	input irrelevance
pig repeated runs	identical output	determinism

Edge Cases

One subtle edge case is trailing whitespace preservation in the ASCII art. If any line loses leading or trailing spaces, the pig’s shape becomes visually incorrect even though the program is logically “correct.” The raw string approach avoids this entirely by preserving formatting verbatim.

Another edge case is accidental escape interpretation of backslashes. For example, writing / \ without raw strings may lead Python to misinterpret \ as an escape prefix. The chosen representation ensures each backslash is treated as a literal character.

Finally, some implementations might attempt to conditionally print only when input equals "pig". While this works under the given constraints, it introduces an unnecessary dependency on input correctness. Since the problem guarantees a single valid input format, the safest approach is unconditional output, which removes an entire class of failure scenarios.