제출 #709772

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
709772		KoD	Radio Towers (IOI22_towers)	C++17	17 / 100	1162 ms	15348 KiB

towers

#include "towers.h"

#include <vector>
#include <iostream>
#include <algorithm>
#include <utility>
#include <numeric>
#include <limits>
#include <iterator>
#include <tuple>
#include <cassert>

namespace kod {

using std::vector;
using std::cerr;
using std::endl;
using std::begin;
using std::end;
using std::pair;
using std::tuple;

template <class F>
struct make_fixed : private F {
    explicit make_fixed(F&& f) : F(std::forward<F>(f)) {}
    template <class... Args> decltype(auto) operator()(Args&&... args) const {
        return F::operator()(*this, std::forward<Args>(args)...);
    }
};

int N;
vector<int> H;

vector<int> par, stack;
vector<vector<int>> child;
vector<pair<int, int>> sum;

void init() {
    par.assign(N, -1);
    for (int i = 0; i < N; ++i) {
        int j = -1;
        while (!stack.empty() and H[stack.back()] < H[i]) {
            j = stack.back();
            stack.pop_back();
        }
        if (j != -1) par[j] = i;
        if (!stack.empty()) par[i] = stack.back();
        stack.push_back(i);
    }
    int root = -1;
    child.resize(N);
    for (int i = 0; i < N; ++i) {
        if (par[i] == -1) root = i;
        else child[par[i]].push_back(i);
    }
    make_fixed([&](auto&& dfs, const int u) -> int {
        int min = H[u];
        for (const int v : child[u]) {
            const int m = dfs(v);
            min = std::min(min, m);
            sum.emplace_back(H[u] - m, 1);
            sum.emplace_back(H[v] - m, -1);
        }
        return min;
    })(root);
    std::sort(begin(sum), end(sum));
    for (int i = (int)sum.size() - 1; i > 0; --i) {
        sum[i - 1].second += sum[i].second;
    }
}

int solve(const int L, const int R, const int D) {
    assert(L == 0 and R == N - 1);
    return std::max(1, std::lower_bound(begin(sum), end(sum), pair(D, 0))->second);
}

}

void init(int N, std::vector<int> H) {
    kod::N = N;
    kod::H = H;
    kod::init();
}

int max_towers(int L, int R, int D) {
    return kod::solve(L, R, D);
}

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