Codeforces: Round 1004 (Div. 1)

Author: Macesuted

Codeforces/2066A.cpp

@@ -0,0 +1,66 @@
+/**
+ * @file 2066A.cpp
+ * @author Macesuted ([email protected])
+ * @date 2025-02-11
+ *
+ * @copyright Copyright (c) 2025
+ *
+ */
+
+#include <bits/stdc++.h>
+using namespace std;
+
+#ifndef LOCAL
+#define endl '\n'
+#endif
+
+bool mem1;
+
+#define maxn 200005
+
+int a[maxn], pos[maxn];
+bool vis[maxn];
+
+int query(int x, int y) {
+    cout << "? " << x << ' ' << y << endl;
+    int v;
+    cin >> v;
+    return v;
+}
+
+void solve(void) {
+    int n;
+    cin >> n;
+    for (int i = 1; i <= n; i++) cin >> a[i], vis[i] = false, pos[a[i]] = i;
+    for (int i = 1; i <= n; i++) vis[a[i]] = true;
+
+    int p = 0;
+    for (int i = 1; i <= n; i++)
+        if (!vis[i]) p = i;
+
+    if (p) {
+        int v = query(p, p % n + 1);
+        return cout << "! " << "AB"[v > 0] << endl, void();
+    }
+
+    int v = query(pos[1], pos[n]), w = query(pos[n], pos[1]);
+    cout << "! " << "AB"[v >= n - 1 && w >= n - 1] << endl;
+    return;
+}
+
+bool mem2;
+
+int main() {
+#ifdef LOCAL
+    cerr << "Memory Cost: " << abs(&mem1 - &mem2) / 1024. / 1024. << "MB" << endl;
+#endif
+
+    int _ = 1;
+    cin >> _;
+    while (_--) solve();
+
+#ifdef LOCAL
+    cerr << "Time Cost: " << clock() * 1000. / CLOCKS_PER_SEC << "MS" << endl;
+#endif
+    return 0;
+}

Codeforces/2066B.cpp

@@ -0,0 +1,67 @@
+/**
+ * @file 2066B.cpp
+ * @author Macesuted ([email protected])
+ * @date 2025-02-11
+ *
+ * @copyright Copyright (c) 2025
+ *
+ */
+
+#include <bits/stdc++.h>
+using namespace std;
+
+#ifndef LOCAL
+#define endl '\n'
+#endif
+
+bool mem1;
+
+#define maxn 200005
+
+int a[maxn], b[maxn], mv[maxn];
+
+void solve(void) {
+    int n;
+    cin >> n;
+    int cnt0 = 0;
+    for (int i = 1; i <= n; i++) cin >> a[i], cnt0 += (a[i] == 0);
+
+    if (!cnt0) return cout << n << endl, void();
+
+    bool met = false;
+    int m = 0;
+    for (int i = 1; i <= n; i++)
+        if (a[i] || !met) b[++m] = a[i], met |= (a[i] == 0);
+
+    bool chk = true;
+    unordered_set<int> S;
+    mv[0] = INT_MAX;
+    for (int i = 1; i <= m; i++) mv[i] = min(mv[i - 1], b[i]);
+    for (int i = m, mex = 0; i > 1 && chk; i--) {
+        S.insert(b[i]);
+        while (S.count(mex)) mex++;
+        if (mv[i - 1] < mex) chk = false;
+    }
+
+    cout << (chk ? m : m - 1) << endl;
+
+    return;
+}
+
+bool mem2;
+
+int main() {
+    ios::sync_with_stdio(false), cin.tie(nullptr);
+#ifdef LOCAL
+    cerr << "Memory Cost: " << abs(&mem1 - &mem2) / 1024. / 1024. << "MB" << endl;
+#endif
+
+    int _ = 1;
+    cin >> _;
+    while (_--) solve();
+
+#ifdef LOCAL
+    cerr << "Time Cost: " << clock() * 1000. / CLOCKS_PER_SEC << "MS" << endl;
+#endif
+    return 0;
+}

Codeforces/2066C.cpp

@@ -0,0 +1,64 @@
+/**
+ * @file 2066C.cpp
+ * @author Macesuted ([email protected])
+ * @date 2025-02-11
+ *
+ * @copyright Copyright (c) 2025
+ *
+ */
+
+#include <bits/stdc++.h>
+using namespace std;
+
+#ifndef LOCAL
+#define endl '\n'
+#endif
+
+bool mem1;
+
+#define maxn 200005
+#define mod 1'000'000'007
+
+int a[maxn], pre[maxn];
+
+int Mod(int x) { return x >= mod ? x - mod : x; }
+
+void solve(void) {
+    int n;
+    cin >> n;
+    for (int i = 1; i <= n; i++) cin >> a[i], pre[i] = pre[i - 1] ^ a[i];
+
+    unordered_map<int, int> f;
+    f[0] = 1;
+    for (int i = 1; i <= n; i++) {
+        int det = 0;
+        if (f.count(pre[i - 1])) det = Mod(det + Mod(2 * f[pre[i - 1]]));
+        if (f.count(pre[i])) det = Mod(det + Mod(2 * f[pre[i]]));
+        if (det) f[pre[i - 1]] = Mod(f[pre[i - 1]] + det);
+    }
+
+    int ans = 0;
+    for (auto [i, v] : f) ans = Mod(ans + v);
+
+    cout << ans << endl;
+
+    return;
+}
+
+bool mem2;
+
+int main() {
+    ios::sync_with_stdio(false), cin.tie(nullptr);
+#ifdef LOCAL
+    cerr << "Memory Cost: " << abs(&mem1 - &mem2) / 1024. / 1024. << "MB" << endl;
+#endif
+
+    int _ = 1;
+    cin >> _;
+    while (_--) solve();
+
+#ifdef LOCAL
+    cerr << "Time Cost: " << clock() * 1000. / CLOCKS_PER_SEC << "MS" << endl;
+#endif
+    return 0;
+}

Codeforces/2066D1.cpp

@@ -0,0 +1,80 @@
+/**
+ * @file 2066D1.cpp
+ * @author Macesuted ([email protected])
+ * @date 2025-02-11
+ *
+ * @copyright Copyright (c) 2025
+ *
+ */
+
+#include <bits/stdc++.h>
+using namespace std;
+
+#ifndef LOCAL
+#define endl '\n'
+#endif
+
+bool mem1;
+
+#define maxn 105
+#define maxm 10005
+#define mod 1'000'000'007
+
+int a[maxm], f[maxn][maxm];
+int64_t fac[maxm], ifac[maxm];
+
+int64_t qpow(int64_t a, int64_t x) {
+    int64_t ans = 1;
+    while (x) {
+        if (x & 1) ans = ans * a % mod;
+        a = a * a % mod, x >>= 1;
+    }
+    return ans;
+}
+int64_t inv(int64_t a) { return qpow(a, mod - 2); }
+
+int Mod(int x) { return x >= mod ? x - mod : x; }
+
+int64_t C(int n, int m) { return fac[n] * ifac[m] % mod * ifac[n - m] % mod; }
+
+void solve(void) {
+    int n, c, m;
+    cin >> n >> c >> m;
+    for (int i = 1; i <= m; i++) cin >> a[i];
+
+    for (int i = 1; i <= n; i++)
+        for (int j = 1; j <= m; j++) f[i][j] = 0;
+
+    f[n][c] = 1;
+    for (int i = n - 1; i >= 1; i--)
+        for (int j = c; j <= m; j++)
+            if (f[i + 1][j])
+                for (int k = 0; k <= min(m - j, c); k++) f[i][j + k] = (f[i][j + k] + f[i + 1][j] * C(c, k)) % mod;
+
+    cout << f[1][m] << endl;
+
+    return;
+}
+
+bool mem2;
+
+int main() {
+    ios::sync_with_stdio(false), cin.tie(nullptr);
+#ifdef LOCAL
+    cerr << "Memory Cost: " << abs(&mem1 - &mem2) / 1024. / 1024. << "MB" << endl;
+#endif
+
+    fac[0] = ifac[0] = 1;
+    for (int i = 1; i < maxm; i++) fac[i] = fac[i - 1] * i % mod;
+    ifac[maxm - 1] = inv(fac[maxm - 1]);
+    for (int i = maxm - 2; i; i--) ifac[i] = ifac[i + 1] * (i + 1) % mod;
+
+    int _ = 1;
+    cin >> _;
+    while (_--) solve();
+
+#ifdef LOCAL
+    cerr << "Time Cost: " << clock() * 1000. / CLOCKS_PER_SEC << "MS" << endl;
+#endif
+    return 0;
+}