Submission #1079409

#	Time	Username	Problem	Language	Result	Execution time	Memory
1079409		Forested	Aliens (IOI16_aliens)	C++17	100 / 100	235 ms	4784 KiB

aliens

#ifndef LOCAL
#define FAST_IO
#endif

// ============
#include <bits/stdc++.h>
#define OVERRIDE(a, b, c, d, ...) d
#define REP2(i, n) for (i32 i = 0; i < (i32)(n); ++i)
#define REP3(i, m, n) for (i32 i = (i32)(m); i < (i32)(n); ++i)
#define REP(...) OVERRIDE(__VA_ARGS__, REP3, REP2)(__VA_ARGS__)
#define PER2(i, n) for (i32 i = (i32)(n)-1; i >= 0; --i)
#define PER3(i, m, n) for (i32 i = (i32)(n)-1; i >= (i32)(m); --i)
#define PER(...) OVERRIDE(__VA_ARGS__, PER3, PER2)(__VA_ARGS__)
#define ALL(x) begin(x), end(x)
#define LEN(x) (i32)(x.size())
using namespace std;
using u32 = unsigned int;
using u64 = unsigned long long;
using i32 = signed int;
using i64 = signed long long;
using f64 = double;
using f80 = long double;
using pi = pair<i32, i32>;
using pl = pair<i64, i64>;
template <typename T>
using V = vector<T>;
template <typename T>
using VV = V<V<T>>;
template <typename T>
using VVV = V<V<V<T>>>;
template <typename T>
using VVVV = V<V<V<V<T>>>>;
template <typename T>
using PQR = priority_queue<T, V<T>, greater<T>>;
template <typename T>
bool chmin(T &x, const T &y) {
    if (x > y) {
        x = y;
        return true;
    }
    return false;
}
template <typename T>
bool chmax(T &x, const T &y) {
    if (x < y) {
        x = y;
        return true;
    }
    return false;
}
template <typename T>
i32 lob(const V<T> &arr, const T &v) {
    return (i32)(lower_bound(ALL(arr), v) - arr.begin());
}
template <typename T>
i32 upb(const V<T> &arr, const T &v) {
    return (i32)(upper_bound(ALL(arr), v) - arr.begin());
}
template <typename T>
V<i32> argsort(const V<T> &arr) {
    V<i32> ret(arr.size());
    iota(ALL(ret), 0);
    sort(ALL(ret), [&](i32 i, i32 j) -> bool {
        if (arr[i] == arr[j]) {
            return i < j;
        } else {
            return arr[i] < arr[j];
        }
    });
    return ret;
}
#ifdef INT128
using u128 = __uint128_t;
using i128 = __int128_t;
#endif
[[maybe_unused]] constexpr i32 INF = 1000000100;
[[maybe_unused]] constexpr i64 INF64 = 3000000000000000100;
struct SetUpIO {
    SetUpIO() {
#ifdef FAST_IO
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
#endif
        cout << fixed << setprecision(15);
    }
} set_up_io;
void scan(char &x) { cin >> x; }
void scan(u32 &x) { cin >> x; }
void scan(u64 &x) { cin >> x; }
void scan(i32 &x) { cin >> x; }
void scan(i64 &x) { cin >> x; }
void scan(string &x) { cin >> x; }
template <typename T>
void scan(V<T> &x) {
    for (T &ele : x) {
        scan(ele);
    }
}
void read() {}
template <typename Head, typename... Tail>
void read(Head &head, Tail &...tail) {
    scan(head);
    read(tail...);
}
#define CHAR(...)     \
    char __VA_ARGS__; \
    read(__VA_ARGS__);
#define U32(...)     \
    u32 __VA_ARGS__; \
    read(__VA_ARGS__);
#define U64(...)     \
    u64 __VA_ARGS__; \
    read(__VA_ARGS__);
#define I32(...)     \
    i32 __VA_ARGS__; \
    read(__VA_ARGS__);
#define I64(...)     \
    i64 __VA_ARGS__; \
    read(__VA_ARGS__);
#define STR(...)        \
    string __VA_ARGS__; \
    read(__VA_ARGS__);
#define VEC(type, name, size) \
    V<type> name(size);       \
    read(name);
#define VVEC(type, name, size1, size2)    \
    VV<type> name(size1, V<type>(size2)); \
    read(name);
// ============

#ifdef DEBUGF
#else
#define DBG(...) (void)0
#endif


class CHT {
    deque<pl> lines;
    static i64 fdiv(i64 x, i64 y) { return x / y - ((x ^ y) < 0 && x % y); }
    static i64 inter(pl l0, pl l1) {
        // ax + b = cx + d
        // (a - c) x = d - b
        // x = (d - b) / (a - c)
        return (l1.second - l0.second) / (l0.first - l1.first);
    }
    static bool is_needed(pl l0, pl l1, pl l2) {
        return inter(l0, l1) < inter(l1, l2);
    }

public:
    CHT() : lines() {}
    void add(i64 a, i64 b) {
        while (LEN(lines) >= 2 &&
               !is_needed(lines[LEN(lines) - 2], lines.back(), pl(a, b))) {
            lines.pop_back();
        }
        lines.emplace_back(a, b);
    }
    i64 get(i64 x) {
        while (LEN(lines) >= 2 && lines[0].first * x + lines[0].second >
                                      lines[1].first * x + lines[1].second) {
            lines.pop_front();
        }
        return lines[0].first * x + lines[0].second;
    }
};

i64 take_photos(i32 n, i32 m, i32 k, V<i32> r, V<i32> c) {
    V<pi> pts(n);
    REP(i, n) {
        pts[i] = pi(r[i], c[i]);
        if (pts[i].first > pts[i].second) {
            swap(pts[i].first, pts[i].second);
        }
    }
    DBG(pts);
    sort(ALL(pts), [&](const pi &p, const pi &q) -> bool {
        if (p.first != q.first) {
            return p.first < q.first;
        } else {
            return p.second > q.second;
        }
    });
    DBG(pts);
    r.clear();
    c.clear();
    i32 ym = -1;
    for (auto [x, y] : pts) {
        if (chmax(ym, y)) {
            r.push_back(x);
            c.push_back(y);
        }
    }
    DBG(r, c);
    n = LEN(r);
    chmin(k, n);

    auto relaxed = [&](i64 lambda) -> i64 {
        CHT cht;
        cht.add(-2LL * r[0], (i64)r[0] * r[0] + lambda);
        i64 mem = 0;
        REP(i, n) {
            mem = cht.get(c[i] + 1) + (i64)(c[i] + 1) * (c[i] + 1);
            if (i != n - 1) {
                i64 a = -2LL * r[i + 1];
                i64 b = mem + (i64)r[i + 1] * r[i + 1] + lambda;
                if (r[i + 1] <= c[i]) {
                    b -= (i64)(c[i] - r[i + 1] + 1) * (c[i] - r[i + 1] + 1);
                }
                cht.add(a, b);
            }
        }
        return mem - k * lambda;
    };

    i64 ok = 0, ng = (i64)m * m;
    while (ng - ok > 1) {
        i64 mid = (ok + ng) / 2;
        if (relaxed(mid) < relaxed(mid + 1)) {
            ok = mid;
        } else {
            ng = mid;
        }
    }
    i64 ans = relaxed(ng);
    return ans;
}

• Subtask 1: 4 / 4
• Subtask 2: 12 / 12
• Subtask 3: 9 / 9
• Subtask 4: 16 / 16
• Subtask 5: 19 / 19
• Subtask 6: 40 / 40