Submission #720128

#	Time	Username	Problem	Language	Result	Execution time	Memory
720128		Cyanmond	Lasers (NOI19_lasers)	C++17	100 / 100	542 ms	36648 KiB

lasers

#include <bits/stdc++.h>

using i64 = long long;

void solve() {
    int L, R;
    std::cin >> L >> R;
    std::map<int, int> stamps;
    while (R--) {
        int X;
        std::cin >> X;
        std::vector<int> W(X);
        for (auto &e : W) std::cin >> e;
        std::vector<int> sumW(X + 1);
        for (int i = 0; i < X; ++i) sumW[i + 1] = sumW[i] + W[i];
        auto calcSum = [&](int l, int r) {
            return sumW[r] - sumW[l];
        };
        std::map<int, int> rls;
        for (int i = 0; i <= X; ++i) {
            const auto l = calcSum(0, i), r = L - calcSum(i, X);
            ++rls[l];
            --rls[r];
        }
        int val = 0, lastPos = 0;
        for (const auto &[p, v] : rls) {
            if (val == 0) {
                ++stamps[lastPos];
                --stamps[p];
            }
            val += v;
            lastPos = p;
        }
    }
    int val = 0, lastPos = 0, answer = 0;
    for (const auto &[p, v] : stamps) {
        if (val != 0) answer += p - lastPos;
        val += v;
        lastPos = p;
    }
    std::cout << answer << std::endl;
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    solve();
}

• Subtask 1: 10 / 10
• Subtask 2: 14 / 14
• Subtask 3: 20 / 20
• Subtask 4: 21 / 21
• Subtask 5: 22 / 22
• Subtask 6: 13 / 13