AGC problems

Author: dolphingarlic

Atcoder/AGC 001-A.cpp

@@ -0,0 +1,15 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int l[100];
+
+int main() {
+    int n;
+    cin >> n;
+    for (int i = 0; i < 2 * n; i++) cin >> l[i];
+    sort(l, l + 2 * n);
+    int ans = 0;
+    for (int i = 0; i < 2 * n; i += 2) ans += l[i];
+    cout << ans;
+    return 0;
+}

Atcoder/AGC 001-B.cpp

@@ -0,0 +1,17 @@
+#include <bits/stdc++.h>
+typedef long long ll;
+using namespace std;
+
+ll lozenge(ll n, ll m) {
+    if (!n) return -m;
+    return m / n * 2 * n + lozenge(m % n, n);
+}
+
+int main() {
+    cin.tie(0)->sync_with_stdio(0);
+    ll n, x;
+    cin >> n >> x;
+    if (x * 2 > n) x = n - x;
+    cout << n + lozenge(x, n - x);
+    return 0;
+}

Atcoder/AGC 002-A.cpp

@@ -0,0 +1,12 @@
+#include <bits/stdc++.h>
+typedef long long ll;
+using namespace std;
+
+int main() {
+    cin.tie(0)->sync_with_stdio(0);
+    int a, b;
+    cin >> a >> b;
+    if (a <= 0 && b >= 0) return cout << "Zero", 0;
+    cout << ((min(b, 0) - min(a, -1)) % 2 ? "Positive" : "Negative");
+    return 0;
+}

Atcoder/AGC 002-B.cpp

@@ -0,0 +1,23 @@
+#include <bits/stdc++.h>
+typedef long long ll;
+using namespace std;
+
+bool has_red[100001];
+int cnt[100001];
+
+int main() {
+    cin.tie(0)->sync_with_stdio(0);
+    int n, m;
+    cin >> n >> m;
+    fill(cnt + 1, cnt + n + 1, 1);
+    has_red[1] = true;
+    while (m--) {
+        int x, y;
+        cin >> x >> y;
+        if (has_red[x]) has_red[y] = true;
+        cnt[x]--, cnt[y]++;
+        if (!cnt[x]) has_red[x] = false;
+    }
+    cout << accumulate(has_red + 1, has_red + n + 1, 0);
+    return 0;
+}

Atcoder/AGC 003-A.cpp

@@ -0,0 +1,18 @@
+#include <bits/stdc++.h>
+typedef long long ll;
+using namespace std;
+
+int main() {
+    cin.tie(0)->sync_with_stdio(0);
+    string s;
+    cin >> s;
+    bool nn = false, ee = false, ww = false, ss = false;
+    for (char c : s) {
+        if (c == 'N') nn = true;
+        if (c == 'E') ee = true;
+        if (c == 'W') ww = true;
+        if (c == 'S') ss = true;
+    }
+    cout << ((nn ^ ss) || (ee ^ ww) ? "No" : "Yes");
+    return 0;
+}

Atcoder/AGC 003-B.cpp

@@ -0,0 +1,22 @@
+#include <bits/stdc++.h>
+typedef long long ll;
+using namespace std;
+
+ll a[100001];
+
+int main() {
+    cin.tie(0)->sync_with_stdio(0);
+    int n;
+    cin >> n;
+    for (int i = 0; i < n; i++) cin >> a[i];
+    ll ans = 0;
+    for (int i = 0; i < n; i++) {
+        ans += a[i] / 2;
+        if ((a[i] & 1) && a[i + 1]) {
+            a[i + 1]--;
+            ans++;
+        }
+    }
+    cout << ans;
+    return 0;
+}

Atcoder/AGC 003-C.cpp

@@ -0,0 +1,21 @@
+#include <bits/stdc++.h>
+typedef long long ll;
+using namespace std;
+
+int x[100001];
+
+int main() {
+    cin.tie(0)->sync_with_stdio(0);
+    int n;
+    cin >> n;
+    map<int, int> pos;
+    for (int i = 0; i < n; i++) {
+        cin >> x[i];
+        pos[x[i]] = i;
+    }
+    sort(x, x + n);
+    int ans = 0;
+    for (int i = 0; i < n; i += 2) if (abs(i - pos[x[i]]) & 1) ans++;
+    cout << ans;
+    return 0;
+}

Atcoder/AGC 017-D.cpp

@@ -0,0 +1,28 @@
+#include <bits/stdc++.h>
+typedef long long ll;
+using namespace std;
+
+vector<int> graph[100001];
+int grundy[100001];
+
+void dfs(int node = 1, int parent = 0) {
+    for (int i : graph[node]) if (i != parent) {
+        dfs(i, node);
+        grundy[node] ^= grundy[i] + 1;
+    }
+}
+
+int main() {
+    cin.tie(0)->sync_with_stdio(0);
+    int n;
+    cin >> n;
+    for (int i = 1; i < n; i++) {
+        int u, v;
+        cin >> u >> v;
+        graph[u].push_back(v);
+        graph[v].push_back(u);
+    }
+    dfs();
+    cout << (grundy[1] ? "Alice" : "Bob");
+    return 0;
+}

Atcoder/AGC 025-B.cpp

@@ -0,0 +1,41 @@
+#include <bits/stdc++.h>
+typedef long long ll;
+using namespace std;
+
+const ll MOD = 998244353;
+
+ll inv(ll base) {
+    ll ans = 1, pow = MOD - 2;
+    while (pow) {
+        if (pow & 1) ans = ans * base % MOD;
+        base = base * base % MOD;
+        pow >>= 1;
+    }
+    return ans;
+}
+
+ll fact[300001];
+
+ll choose(ll n, ll m) {
+    return fact[n] * inv(fact[m]) % MOD * inv(fact[n - m]) % MOD;
+}
+
+int main() {
+    cin.tie(0)->sync_with_stdio(0);
+    int n;
+    ll a, b, k;
+    cin >> n >> a >> b >> k;
+
+    fact[0] = 1;
+    for (int i = 1; i <= n; i++) fact[i] = fact[i - 1] * i % MOD;
+
+    ll ans = 0;
+    for (ll a_cnt = 0; a_cnt <= n && a * a_cnt <= k; a_cnt++) {
+        ll b_sum = k - a * a_cnt;
+        ll b_cnt = b_sum / b;
+        if (b_sum % b != 0 || b_cnt > n) continue;
+        ans = (ans + choose(n, a_cnt) * choose(n, b_cnt)) % MOD;
+    }
+    cout << ans;
+    return 0;
+}

Atcoder/AGC 035-B.cpp

@@ -0,0 +1,41 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+vector<int> graph[100001];
+int visited[100001], odd[100001], timer = 1;
+vector<pair<int, int>> ans;
+
+void dfs(int node, int parent = 0) {
+    visited[node] = timer++;
+    for (int i : graph[node]) if (i != parent) {
+        if (!visited[i]) {
+            dfs(i, node);
+            if (odd[i]) {
+                ans.push_back({i, node});
+                odd[i] = 0;
+            } else {
+                ans.push_back({node, i});
+                odd[node] ^= 1;
+            }
+        } else if (visited[node] > visited[i]) {
+            ans.push_back({node, i});
+            odd[node] ^= 1;
+        }
+    }
+}
+
+int main() {
+    cin.tie(0)->sync_with_stdio(0);
+    int n, m;
+    scanf("%d %d", &n, &m);
+    while (m--) {
+        int u, v;
+        scanf("%d %d", &u, &v);
+        graph[u].push_back(v);
+        graph[v].push_back(u);
+    }
+    for (int i = 1; i <= n; i++) if (!visited[i]) dfs(i);
+    if (accumulate(odd + 1, odd + n + 1, 0)) printf("-1");
+    else for (pair<int, int> i : ans) printf("%d %d\n", i.first, i.second);
+    return 0;
+}