Editing 0721 - CD (section)

== Rezolvare ==
<syntaxhighlight lang="python" line>
#0721 - CD
def read_input(file_name):
    try:
        with open(file_name, 'r') as file:
            n, S = map(int, file.readline().split())
            data = [tuple(map(int, line.split())) for line in file.readlines()]

            if not (2 <= n <= 300 and S % n == 0 and all(0 <= y <= 1000 and 1 <= c <= n for y, c in data)):
                raise ValueError("Numerele nu respecta restricțiile.")

            return n, S, data
    except Exception as e:
        print(f"Nu au fost respectate cerintele impuse: {str(e)}")
        return None


def write_output(file_name, result):
    with open(file_name, 'w') as file:
        if result is not None:
            file.write(f"{result}\n")


def count_ways(n, S, data):
    mod = 9901
    dp = [0] * (S + 1)
    dp[0] = 1

    for y, c in data:
        for i in range(S, y - 1, -1):
            dp[i] = (dp[i] + dp[i - y] - dp[i - y - 1] + mod) % mod

    return dp[S]


def main(input_file, output_file):
    result = read_input(input_file)
    if result is not None:
        n, S, data = result
        result = count_ways(n, S, data)
        write_output(output_file, result)


if __name__ == "__main__":
    main("cdin.txt", "cdout.txt")

</syntaxhighlight>