Joisc2007

Sun, 25 Jan 2026 00:20:52 +0900

https://atcoder.jp/contests/abcjoisc2007

score. 得点 (Score)

https://atcoder.jp/contests/joisc2007/tasks/joisc2007_score

factorial. 階乗 (Factorial)

https://atcoder.jp/contests/joisc2007/tasks/joisc2007_factor

mall. ショッピングモール (Mall)

https://atcoder.jp/contests/joisc2007/tasks/joisc2007_mall

building. ビルの飾り付け (Building)

https://atcoder.jp/contests/joisc2007/tasks/joisc2007_buildi

fermat. フェルマー方程式 (Fermat)

https://atcoder.jp/contests/joisc2007/tasks/joisc2007_fermat

salt. SALT TREE XV

https://atcoder.jp/contests/joisc2007/tasks/joisc2007_salt

anagram. アナグラム (Anagram)

https://atcoder.jp/contests/joisc2007/tasks/joisc2007_anagra

2026/1/25 自力 AC

https://kenkoooo.com/atcoder/#/contest/show/d1b52ca5-dd9a-4c44-a49c-47f405fa737e

void solve() {
 ios_base::sync_with_stdio(false);
 cin.tie(nullptr);

 string S;
 cin >> S;
 vll cnt(26);
 for (char c : S) cnt[c - 'A']++;

 vll fac(21);
 fac[0] = 1;
 rep(i, 20) fac[i + 1] = fac[i] * (i + 1);

 reverse(all(S));

 auto f = [&](auto f, string s) -> ll {
 if (s == "") return 1;
 int up = s.back() - 'A';

 ll sum = 0;
 rep(i, up) {
 if (cnt[i] == 0) continue;
 cnt[i]--;

 ll num = 0, den = 1;
 rep(j, 26) {
 if (cnt[j]) {
 num += cnt[j];
 den *= fac[cnt[j]];
 }
 }
 sum += fac[num] / den;

 cnt[i]++;
 }
 s.pop_back();
 cnt[up]--;
 return sum + f(f, s);
 };

 cout << f(f, S) << endl;
}

route. 象使い (Route)

https://atcoder.jp/contests/joisc2007/tasks/joisc2007_route

Joi2012yo

Fri, 19 Sep 2025 02:43:42 +0900

https://atcoder.jp/contests/abcjoi2012yo

A. ランチ (Lunch)

https://atcoder.jp/contests/joi2012yo/tasks/joi2012yo_a

B. サッカー (Soccer)

https://atcoder.jp/contests/joi2012yo/tasks/joi2012yo_b

C. 最高のピザ (Best Pizza)

https://atcoder.jp/contests/joi2012yo/tasks/joi2012yo_c

D. パスタ (Pasta)

https://atcoder.jp/contests/joi2012yo/tasks/joi2012yo_d

E. イルミネーション (Illumination)

https://atcoder.jp/contests/joi2012yo/tasks/joi2012yo_e

F. ジグザグ数 (Zig-Zag Numbers)

https://atcoder.jp/contests/joi2012yo/tasks/joi2012yo_f

桁 DP 解法だということをわかった状態で自力 AC.

void solve() {
 ios_base::sync_with_stdio(false);
 cin.tie(nullptr);

 modint::set_mod(10000);
 using mint = modint;

 auto f = [&](string X, ll MOD) -> mint {
 int N = X.size();

 // dp[is_less][prev number][dir][mod]
 // dir: 0 不定, 1 up, 2 down
 vector dp(2, vector(10, vector(3, vector<mint>(MOD))));
 dp[0][0][0][0] = 1;

 rep(i, N) {
 int t = X[i] - '0';
 vector dpn(2, vector(10, vector(3, vector<mint>(MOD))));

 rep(d, 10) rep(is_less, 2) rep(prev_number, 10) rep(dir, 3) rep(mod, MOD) {
 if (!is_less && d > t) continue;
 if (dir == 1 && prev_number <= d) continue;
 if (dir == 2 && prev_number >= d) continue;
 if (dir == 0 && d != 0 && prev_number == d) continue;

 int is_less_n = is_less || d < t;
 int dir_n = 0;
 if (dir == 0 && prev_number == 0) {
 dir_n = 0;
 } else if (prev_number < d) {
 dir_n = 1;
 } else if (prev_number > d) {
 dir_n = 2;
 }

 int mod_n = (mod * 10 + d) % MOD;

 dpn[is_less_n][d][dir_n][mod_n] += dp[is_less][prev_number][dir][mod];
 }

 swap(dp, dpn);
 }

 mint ans = 0;
 rep(is_less, 2) rep(d, 10) rep(dir, 3) {
 ans += dp[is_less][d][dir][0];
 }

 // cout << ans << endl;

 return ans;
 };

 string A, B;
 ll M;
 cin >> A >> B >> M;

 ll zigzag = 0;
 {
 ll m = (A[0] - '0') % M;
 rep2(i, 1, (ll)A.size()) {
 m *= 10;
 m += A[i] - '0';
 m %= M;
 }

 int ok = 1;
 rep(i, (ll)A.size() - 1) {
 if (A[i] == A[i + 1]) {
 ok = 0;
 break;
 }
 }
 rep2(i, 1, (ll)A.size() - 1) {
 if (A[i - 1] < A[i] && A[i] < A[i + 1]) ok = 0;
 if (A[i - 1] > A[i] && A[i] > A[i + 1]) ok = 0;
 }
 zigzag = m == 0 && ok;
 }

 mint ans = f(B, M) - f(A, M) + zigzag;
 cout << ans.val() << endl;
}

Joi on 競プロメモ

Joisc2007

score. 得点 (Score)

factorial. 階乗 (Factorial)

mall. ショッピングモール (Mall)

building. ビルの飾り付け (Building)

fermat. フェルマー方程式 (Fermat)

salt. SALT TREE XV

anagram. アナグラム (Anagram)

route. 象使い (Route)

Joi2012yo

A. ランチ (Lunch)

B. サッカー (Soccer)

C. 最高のピザ (Best Pizza)

D. パスタ (Pasta)

E. イルミネーション (Illumination)

F. ジグザグ数 (Zig-Zag Numbers)