ABC-211

A

$URL\:\to$

解法

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B

$URL\:\to$

解法

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C

$URL\:\to$ https://atcoder.jp/contests/abc211/tasks/abc211_c

#DP

S = String().content
T = "chokudai"
N = len(S)
dp = [[0]*(N+1) for _ in range(len(T))]
index = {T[i]:i for i in range(len(T))}

for i in range(N):
  for j in range(len(T)):
    dp[j][i+1] = dp[j][i]
    if S[i] in index.keys() and j==index[S[i]]:
      if j>0: dp[j][i+1] += dp[j-1][i+1]
      else: dp[j][i+1] += 1

ans = dp[-1][-1]%(10**9+7)

print(ans)

解法

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D

$URL\:\to$

解法

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E

$URL\:\to$

解法

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