結果

問題 No.324 落ちてた閉路グラフ
コンテスト
ユーザー lam6er
提出日時 2025-03-20 18:58:17
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 3,687 ms / 5,000 ms
コード長 2,727 bytes
コンパイル時間 323 ms
コンパイル使用メモリ 82,328 KB
実行使用メモリ 223,900 KB
最終ジャッジ日時 2025-03-20 18:59:34
合計ジャッジ時間 25,079 ms
ジャッジサーバーID
（参考情報） 		judge4 / judge2
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 4
other AC * 34
権限があれば一括ダウンロードができます

ソースコード

diff #
raw source code 

n, m = map(int, input().split())
w = list(map(int, input().split()))
if m == 0:
    print(0)
    exit()

max_val = -float('inf')

def case_a():
    if m == 0:
        return 0
    dp = [[-float('inf')] * 2 for _ in range(m + 1)]
    dp[0][0] = 0
    for i in range(1, n):  # Processing vertices 2 to n (0-based i from 1 to n-1)
        current_w = w[i - 1]  # Edge between vertex (i) and (i+1)
        new_dp = [[-float('inf')] * 2 for _ in range(m + 1)]
        for j in range(m + 1):
            for prev_prev in 0, 1:
                if dp[j][prev_prev] == -float('inf'):
                    continue
                # Not selecting current vertex (j remains)
                if new_dp[j][0] < dp[j][prev_prev]:
                    new_dp[j][0] = dp[j][prev_prev]
                # Selecting current vertex if possible
                if j < m:
                    added = current_w if prev_prev else 0
                    new_sum = dp[j][prev_prev] + added
                    if new_dp[j + 1][1] < new_sum:
                        new_dp[j + 1][1] = new_sum
        dp = new_dp
    max_a = max(dp[m][0], dp[m][1])
    return max_a if max_a != -float('inf') else -float('inf')

def case_b():
    target = m - 1
    if target < 0:
        return -float('inf')
    dp = [[-float('inf')] * 2 for _ in range(target + 1)]
    dp[0][1] = 0  # Initially selected vertex 1
    for i in range(1, n):  # Vertices 2 to n (0-based i from 1 to n-1)
        current_w = w[i - 1]
        new_dp = [[-float('inf')] * 2 for _ in range(target + 1)]
        for j in range(target + 1):
            for prev_prev in 0, 1:
                if dp[j][prev_prev] == -float('inf'):
                    continue
                # Not selecting current vertex
                if new_dp[j][0] < dp[j][prev_prev]:
                    new_dp[j][0] = dp[j][prev_prev]
                # Selecting current vertex if possible
                if j < target:
                    added = current_w if prev_prev else 0
                    new_sum = dp[j][prev_prev] + added
                    if new_dp[j + 1][1] < new_sum:
                        new_dp[j + 1][1] = new_sum
        dp = new_dp
    max_b = -float('inf')
    for p in 0, 1:
        if dp[target][p] == -float('inf'):
            continue
        current = dp[target][p]
        if p == 1:  # Last vertex (n) is selected, add edge n if vertex 1 is selected
            current += w[-1]
        if current > max_b:
            max_b = current
    return max_b if max_b != -float('inf') else -float('inf')

caseA = case_a()
caseB = case_b()
max_val = max(caseA, caseB)

possible_zero = m <= (n // 2)
if possible_zero:
    max_val = max(max_val, 0)

print(max_val if max_val != -float('inf') else 0)
0