C - Previous Permutation https://atcoder.jp/contests/abc276/tasks/abc276_c

abc276_c.py

N = int(input())
P = list(map(int, input().split()))

# (1) 末尾の昇順区間を探す
i = N - 1
while i > 0 and P[i - 1] < P[i]:
    i -= 1

# (2) jは、昇順の始まりのひとつ左(交換対象)
j = i - 1

# (3) 交換対象を探す
k = i
while k < N and P[j] > P[k]:
    k += 1
k -= 1

# (4) 交換
P[j], P[k] = P[k], P[j]

# (5) 右側を降順に
P[j + 1 :] = P[:j:-1]

print(*P)