More problems.

2018 ACM-ICPC, Universidad Nacional de Colombia Programming Contest/D. Divorce.cpp

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+/* Problem URL: https://codeforces.com/gym/101845/problem/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+struct pt {
+    ll x, y;
+
+    pt() = default;
+    pt(ll x, ll y): x(x), y(y) {}
+
+    friend istream &operator >> (istream &is, pt &a) {
+        is >> a.x >> a.y;
+        return is;
+    }
+
+    ll operator * (pt b) {
+        return x * b.x + y * b.y;
+    }
+
+    ll operator ^ (pt b) {
+        return x * b.y - y * b.x;
+    }
+
+    pt operator - (pt b) {
+        return pt(x - b.x, y - b.y);
+    }
+};
+
+ll sarea2(pt a, pt b, pt c)
+{
+    return (b - a) ^ (c - a);
+}
+
+int ccw(pt a, pt b, pt c)
+{
+    ll r = sarea2(a, b, c);
+    return (r > 0) - (r < 0);
+}
+
+void pre()
+{
+
+}
+
+#define TEST 0
+
+void solve()
+{
+    int n, m;
+    cin >> n >> m;
+
+    V<pt> pol(n);
+    cin >> pol;
+
+    vl pref(n * 3);
+    nrep(i, 1, n * 3) {
+        pref[i] = pref[i - 1] + sarea2(pt(0, 0), pol[(i - 1) % n], pol[i % n]);
+    }
+
+    ll ans = 0;
+    while (m--) {
+        int l, r;
+        cin >> l >> r;
+        l--, r--;
+
+        if (l > r) {
+            swap(l, r);
+        }
+
+        if ((l + 1) % n == r) {
+            continue;
+        }
+
+        int l2 = r;
+        int r2 = l + n;
+
+        ll ar1 = abs(sarea2(pt(0, 0), pol[r], pol[l]) + pref[r] - pref[l]);
+        ll ar2 = abs(pref[r2] - pref[l2] + sarea2(pt(0, 0), pol[r2 % n], pol[l2 % n]));
+
+        rmax(ans, min(ar1, ar2));
+    }
+
+    cout << ans / 2.0 << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}