ABC326をPythonで（A～F）

パナソニックグループ プログラミングコンテスト2023（AtCoder Beginner Contest 326）

A問題

A

x, y = map(int, input().split())
print("Yes" if x - 3 <= y <= x + 2 else "No")

B問題

全探索

B

n = int(input())
while True:
    x = str(n)
    if int(x[0]) * int(x[1]) == int(x[2]):
        print(n)
        exit()
    else:
        n += 1

C問題

尺取り

C

n, m = map(int, input().split())
a = sorted(map(int, input().split()))

right = 0
ans = 0
for left in range(n):
    while right < n and a[right] - a[left] < m:
        right += 1
    ans = max(ans, right - left)

print(ans)

D問題

DFSを使った全探索
ただし、全パターンを調べると間に合わないので足切りをしっかりする。

D

n = int(input())
R = input()
C = input()

ans = [["."] * n for _ in range(n)]
set_list = [[] for _ in range(n)]
d = {"A":["ABC", "ACB"], "B":["BAC", "BCA"], "C":["CAB", "CBA"]}

def DFS(i=0):
    if i == n:
        for j in range(n):
            if set(set_list[j]) == {"A", "B", "C"} and set_list[j][0] == C[j] and len(set_list[j]) == 3:
                pass
            else:
                return False

        print("Yes")
        for ans_i in ans:print("".join(ans_i))
        exit()

    for p_c in d[R[i]]:
        for c_i in combinations(range(n), 3):
            flag = True
            for j, p_j in zip(c_i, p_c):
                ans[i][j] = p_j
                set_list[j].append(p_j)
                if set_list[j][0] != C[j]:
                    flag = False
            if flag:
                DFS(i + 1)
            for j, p_j in zip(c_i, p_c):
                ans[i][j] = "."
                set_list[j].pop()

DFS()
print("No")

E問題

解説記事を参照

E

n = int(input())
a = [0] +  list(map(int, input().split()))
mod = 998244353
p = pow(n, -1, mod)

# dp[i] = i以降に稼ぐお金の期待値
# dp[i] = a[i] + sum(dp[i+1:]) / n
dp = [0] * (n + 1)
sums = 0
for i in range(n, -1, -1):
    dp[i] = sums * p % mod + a[i]
    dp[i] %= mod
    sums += dp[i]
    sums %= mod

print(dp[0])

F問題

y軸の操作は奇数番目に、x軸の操作は偶数番目にのみ行われる。
よってそれぞれでAの数字を+-で目標の数字にできるか調べる。

目標の数字にできるかは半分全列挙で求められる。

F

def merge(a):
    dic = {0:""}
    for a_i in a:
        new_d = dict()
        for key, val in dic.items():
            if key + a_i not in new_d:
                new_d[key + a_i] = val + "+"
            if key - a_i not in new_d:
                new_d[key - a_i] = val + "-"
        dic = new_d
    return dic

def solve(x, lst):
    S = merge(lst[:len(lst) // 2])
    T = merge(lst[len(lst) // 2:])
    for s_k, s_v in S.items():
        if x - s_k in T:
            return s_v + T[x - s_k]

    print("No")
    exit()

n, X, Y = map(int, input().split())
a = list(map(int, input().split()))

y_list = solve(Y, a[::2])
x_list = solve(X, a[1::2])

ans = []
now = [1, 0]
for i in range(n):
    if i % 2 == 0:
        if y_list[i // 2] == "+" and now == [1, 0]:
            ans.append("L")
            now = [0, 1]
        elif y_list[i // 2] == "-" and now == [-1, 0]:
            ans.append("L")
            now = [0, -1]
        elif y_list[i // 2] == "+" and now == [-1, 0]:
            ans.append("R")
            now = [0, 1]
        elif y_list[i // 2] == "-" and now == [1, 0]:
            ans.append("R")
            now = [0, -1]
    else:
        if x_list[i // 2] == "+" and now == [0, -1]:
            ans.append("L")
            now = [1, 0]
        elif x_list[i // 2] == "-" and now == [0, 1]:
            ans.append("L")
            now = [-1, 0]
        elif x_list[i // 2] == "+" and now == [0, 1]:
            ans.append("R")
            now = [1, 0]
        elif x_list[i // 2] == "-" and now == [0, -1]:
            ans.append("R")
            now = [-1, 0]

print("Yes")
print("".join(ans))