Submission #1287367

#	Time	Username	Problem	Language	Result	Execution time	Memory
1287367		hehehe147	Lasers (NOI19_lasers)	C++20	100 / 100	93 ms	8800 KiB

lasers

#include <bits/stdc++.h>

using namespace std;

int a[500007];


void solve() {
    int n, L;
    cin >> L >> n;
    vector<pair<int, int>> e;
    for (int i = 1; i <= n; i++) {
        int m;
        cin >> m;
        int pref = 0, suff = 0, sum = 0;
        for (int j = 1; j <= m; j++) {
            cin >> a[j];
            sum += a[j];
        }

        for (int j = 1; j <= m; j++) {
            suff = L - sum + pref + 1;
            pref += a[j];
            if (pref >= suff) {
                e.push_back({suff, 1});
                e.push_back({pref + 1, -1});
            }
        }
    }

    e.push_back({L + 1, 0});
    sort(e.begin(), e.end());
    int ans = 0, cnt = 0;
    for (int i = 0; i < e.size(); i++) {
        cnt += e[i].second;
        if (cnt) {
            ans += e[i + 1].first - e[i].first;
        } 
    }
    cout << ans << "\n";
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    if (fopen("laser.inp", "r")) {
        freopen("laser.inp", "r", stdin);
        freopen("laser.out", "w", stdout);
    }

    solve();
}

Compilation message (stderr)

lasers.cpp: In function 'int main()':
lasers.cpp:48:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |         freopen("laser.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
lasers.cpp:49:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   49 |         freopen("laser.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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