Submission #6439470

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Source Code Expand

S = input()
K = int(input())
L = len(S)

dp = [{a: 0 for a in map(chr, range(ord('a'), ord('z')+1))} for _ in range(L+1)]
dp[1][S[-1]] = 1

for i in range(2,L+1):
    s = S[-i]
    dp[i][s] = 1
    for abc in map(chr, range(ord('a'), ord('z')+1)):
        dp[i][abc] += dp[i-1][abc]
        if dp[i-1].get(abc):
            dp[i][s] += dp[i-1][abc]
    dp[i][s] -= dp[i-1][s]

ans = ''
if sum(dp[-1].values()) >= K:
    cnt = K
    pos = 0
    while cnt > 0 and pos < L:
        for abc in map(chr, range(ord('a'), ord('z')+1)):
            if cnt - dp[-pos-1][abc] > 0:
                cnt -= dp[-pos-1][abc]
            else:
                ans += abc
                pos = S.find(abc, pos) + 1
                cnt -= 1
                break

print(ans or 'Eel')

Submission Info

Judge Result