Submission #958797

#TimeUsernameProblemLanguageResultExecution timeMemory
958797relexBoat (APIO16_boat)C++17
9 / 100
2 ms756 KiB
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;
using ll = long long;
using ld = long double;

struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};
gp_hash_table<ll, ll, custom_hash> app;
//constexpr int MOD = 998244353;
constexpr int MOD = 1e9 + 7;

constexpr ll INF = 3e18;



ll n, m, k, q, x, y, z, w, h, T;
string s, t;
double p;

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

    int n;
    cin >> n;

    pair<int, int> a[n];
    set<int> s;
    for (int i = 0; i < n; i++) {
        cin >> a[i].first >> a[i].second;
        s.insert(a[i].first); s.insert(a[i].second);
    }

    map<int, int> app;
    int cur = 1;
    for (int val : s) {
        app[val] = cur++;
    }
    for (int i = 0; i < n; i++) {
        a[i].first = app[a[i].first]; a[i].second = app[a[i].second];
    }

    int pref[cur] = {};
    fill(pref, pref + cur, 1);

    for (int i = 0; i < n; i++) {
        int dp[cur] = {};
        for (int j = a[i].first; j <= a[i].second; j++) {
            dp[j] = pref[j - 1];
        }
        int ad = 0;
        for (int j = 1; j < cur; j++) {
            ad += dp[j];
            if (ad >= MOD) ad -= MOD;
            pref[j] += ad;
            if (pref[j] >= MOD) pref[j] -= MOD;
        }
    }

    int ans = (pref[cur - 1] - 1 + MOD) % MOD;

    printf("%i\n", ans);
}
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