AtCoder & CodeForces tasks from contests

Author: mitkonikov

Diff for: .vscode/settings.json

@@ -14,6 +14,12 @@
         "type_traits": "cpp",
         "xtree": "cpp",
         "xutility": "cpp",
-        "istream": "cpp"
+        "istream": "cpp",
+        "ios": "cpp",
+        "optional": "cpp",
+        "system_error": "cpp",
+        "xlocnum": "cpp",
+        "xtr1common": "cpp",
+        "map": "cpp"
     }
 }

Diff for: AtCoder/A_-_Apple.cpp

@@ -0,0 +1,21 @@
+#include <bits/stdc++.h>
+#define ll long long
+#define endl '\n'
+
+using namespace std;
+
+int main() {
+    int x, y;
+    cin >> x >> y;
+    int n;
+    cin >> n;
+
+    if (x * 3 < y) {
+        cout << n * x << endl;
+    } else {
+        cout << (n / 3) * y + (n % 3) * x << endl;
+    }
+
+    cout << flush;
+    return 0;
+}

Diff for: AtCoder/A_-_Middle_Letter.cpp

@@ -0,0 +1,13 @@
+#include <bits/stdc++.h>
+#define ll long long
+#define endl '\n'
+
+using namespace std;
+
+int main() {
+    string s;
+    cin >> s;
+    cout << s[(s.size() / 2)] << endl;
+    cout << flush;
+    return 0;
+}

Diff for: AtCoder/B_-_Explore.cpp

@@ -0,0 +1,33 @@
+#include <bits/stdc++.h>
+#define ll long long
+#define endl '\n'
+
+using namespace std;
+
+int main() {
+    ll n, m, t;
+    cin >> n >> m >> t;
+    vector<int> a(n-1);
+    for (int i = 0; i < n-1; i++) {
+        cin >> a[i];
+    }
+    vector<int> inc(n-1);
+    for (int i = 0; i < m; i++) {
+        int x, y;
+        cin >> x >> y;
+        x--;
+        inc[x] += y;
+    }
+    bool ok = true;
+    for (int i = 0; i < n-1; i++) {
+        if (t - a[i] + inc[i] <= 0) {
+            ok = false;
+            break;
+        }
+
+        t = t - a[i] + inc[i];
+    }
+    cout << (ok ? "Yes" : "No") << endl;
+    cout << flush;
+    return 0;
+}

Diff for: AtCoder/B_-_Modulo_Number.cpp

@@ -0,0 +1,14 @@
+#include <bits/stdc++.h>
+#define ll long long
+#define endl '\n'
+
+using namespace std;
+
+int main() {
+    ll N;
+    cin >> N;
+    const ll MOD = 998244353;
+    cout << ((N % MOD) + MOD) % MOD << endl;
+    cout << flush;
+    return 0;
+}

Diff for: AtCoder/C_-_Belt_Conveyor.cpp

@@ -0,0 +1,43 @@
+#include <bits/stdc++.h>
+#define ll long long
+#define endl '\n'
+
+using namespace std;
+
+int main() {
+    int n, m;
+    cin >> n >> m;
+    vector<string> mat(n);
+    for (int i = 0; i < n; i++) {
+        cin >> mat[i];
+    }
+    vector<vector<bool>> visited(n, vector<bool>(m, false));
+    int i = 0, j = 0;
+    while (true) {
+        if (visited[i][j]) {
+            cout << -1 << endl;
+            return 0;
+        }
+
+        visited[i][j] = true;
+        int ai = i, aj = j;
+        if (mat[i][j] == 'R') {
+            j++;
+        } else if (mat[i][j] == 'L') {
+            j--;
+        } else if (mat[i][j] == 'U') {
+            i--;
+        } else if (mat[i][j] == 'D') {
+            i++;
+        }
+
+        if (i >= 0 && j >= 0 && i < n && j < m) {
+            continue;
+        } else {
+            cout << ai+1 << " " << aj+1 << endl;
+            break;
+        }
+    }
+    cout << flush;
+    return 0;
+}

Diff for: Binary Search/D_-_Iroha_and_Haiku_New_ABC_Edition.cpp

@@ -0,0 +1,72 @@
+#include <bits/stdc++.h>
+#define ll long long
+#define endl '\n'
+
+using namespace std;
+
+#define ll long long
+// [start,end)
+ll binary_search(function<bool(ll)> func, ll start, ll end) {
+    /* func:int ->bool
+        returns smallest int x where func(x) evaluates to true, searches in [start,end), it is assumed the values are false, .. , false, true ...
+    */
+
+    if (end <= start) return end;   // has to be here, otherwise func(end-1) in next line could be a problem
+    if (!func(end-1)) return end;
+    while (end - start > 1) {
+        ll mid = (start + end) / 2;
+        if (func(mid)) end = mid; else start = mid;
+    }
+
+    return (func(start) ? start : end);
+};
+
+int main() {
+    int n;
+    ll P, Q, R;
+    cin >> n >> P >> Q >> R;
+
+    ll sum = P + Q + R;
+    vector<ll> a(n), pref(n);
+    for (int i = 0; i < n; i++) {
+        cin >> a[i];
+    }
+    
+    pref[0] = a[0];
+    for (int i = 1; i < n; i++) {
+        pref[i] = pref[i-1] + a[i];
+    }
+
+    auto binary = [&](int x, int R, ll sum) {
+        int initR = R;
+        ll cur_pref = (x-1>=0 ? pref[x-1] : 0);
+        int id = binary_search([&](ll id) {
+            return (pref[id] - cur_pref >= sum);
+        }, x, R);
+        if (pref[id] - cur_pref == sum && id + 1 < initR) {
+            return id+1;
+        }
+        return -1;
+    };
+
+    bool ok = false;
+    for (int x = 0; x < n-3; x++) {
+        int w = binary(x, n, sum);
+        if (w == -1) continue;
+        int y = binary(x, w, P);
+        if (y == -1) continue;
+        int z = binary(y, w, Q);
+        if (z == -1) continue;
+        int ww = binary(z, w+1, R);
+        if (ww == -1) continue;
+        if (w == ww && x < y && y < z && z < w) {
+            ok = true;
+            // cout << x << " " << y << " " << z << " " << w << endl;
+            break;
+        }
+    }
+
+    cout << (ok ? "Yes" : "No") << endl;
+    cout << flush;
+    return 0;
+}

Diff for: CodeForces/A_Burenka_Plays_with_Fractions.cpp

@@ -0,0 +1,36 @@
+#include <bits/stdc++.h>
+#define ll long long
+#define endl '\n'
+
+using namespace std;
+
+template<typename T>
+T gcd(T a, T b) {
+    return (a == 0) ? b : gcd(b % a, a);
+}
+
+void testCase() {
+    ll a, b, c, d;
+    cin >> a >> b >> c >> d;
+    if (a * d == b * c) {
+        cout << 0 << endl;
+    } else {
+        if (a % gcd(b, d) != 0 && c % gcd(b, d) != 0) {
+            cout << 2 << endl;
+        } else {
+            cout << 1 << endl;
+        }
+    }
+}
+
+int main() {
+    int t;
+    cin >> t;
+
+    while (t--) {
+        testCase();
+    }
+
+    cout << flush;
+    return 0;
+}

Diff for: CodeForces/A_Chip_Game.cpp

@@ -0,0 +1,29 @@
+#include <bits/stdc++.h>
+#define ll long long
+#define endl '\n'
+
+using namespace std;
+
+void testCase() {
+    int n, m;
+    cin >> n >> m;
+    n--;
+    m--;
+    if ((((n % 2 == 1) && (m % 2 == 0)) || ((n % 2 == 0) && (m % 2 == 1))) && !((n % 2 == 1) && (m % 2 == 1))) {
+        cout << "Burenka" << endl;
+    } else {
+        cout << "Tonya" << endl;
+    }
+}
+
+int main() {
+    int t;
+    cin >> t;
+
+    while (t--) {
+        testCase();
+    }
+
+    cout << flush;
+    return 0;
+}

Diff for: CodeForces/A_Crossmarket.cpp

@@ -0,0 +1,33 @@
+#include <bits/stdc++.h>
+#define ll long long
+#define endl '\n'
+
+using namespace std;
+
+void testCase() {
+    int n, m;
+    cin >> n >> m;
+
+    if (n == 1 && m == 1) {
+        cout << 0 << endl;
+        return;
+    }
+    
+    if (n > m) {
+        cout << m + (m - 1) + (n - 1) << endl;
+    } else {
+        cout << n + (n - 1) + (m - 1) << endl;
+    }
+}
+
+int main() {
+    int t;
+    cin >> t;
+
+    while (t--) {
+        testCase();
+    }
+
+    cout << flush;
+    return 0;
+}

Diff for: CodeForces/A_Wonderful_Permutation.cpp

@@ -0,0 +1,31 @@
+#include <bits/stdc++.h>
+#define ll long long
+#define endl '\n'
+
+using namespace std;
+
+void testCase() {
+    int n, k;
+    cin >> n >> k;
+    vector<int> a(n);
+    for (int i = 0; i < n; i++) cin >> a[i];
+    int count = 0;
+    for (int i = 0; i < k; i++) {
+        if (a[i] > k) {
+            count++;
+        }
+    }
+    cout << count << endl;
+}
+
+int main() {
+    int t;
+    cin >> t;
+
+    while (t--) {
+        testCase();
+    }
+
+    cout << flush;
+    return 0;
+}