Submission #1041213

#	Time	Username	Problem	Language	Result	Execution time	Memory
1041213		ilovveyyou	Trains (BOI24_trains)	C++14	100 / 100	246 ms	361556 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define ll long long
#define pll pair<ll, ll>
#define pii pair<int, int>
#define mp(x, y) make_pair(x, y)
#define sz(v) ((int) (v).size())
#define all(v) (v).begin(), (v).end()
#define MASK(i) (1LL << (i))
#define BIT(x, y) (((x) >> (y)) & 1)
#define clz __builtin_clzll
#define ctz __builtin_ctzll
#define popcount __builtin_popcount
#define lg(x) (63 - clz(x))

template <class X, class Y>
    inline bool maximize(X &x, Y y) {
        return (x < y ? x = y, true : false);
    }
template <class X, class Y>
    inline bool minimize(X &x, Y y) {
        return (x > y ? x = y, true : false);
    }
template <class X>
    inline void compress(vector<X> &a) {
        sort(all(a)); a.resize(unique(all(a)) - a.begin());
    }

const ll oo = (ll) 1e18, inf = (ll) 1e9, mod = (ll) 1e9 + 7;
const int mxn = (int) 2e5 + 5, S = (int) 450, S2 = (int) 450, lg = (int) 17;

void add(ll &x, ll y) {
    x += y;
    if (x >= mod) x -= mod;
}

void sub(ll &x, ll y) {
    x -= y;
    if (x < 0) x += mod;
}


ll n;
pair<ll, ll> a[mxn];

ll f[mxn + S];
ll calc[mxn + S][S+1];

void solve() {

    cin >> n;
    for (int i = 1; i <= n; ++i) {
        cin >> a[i].se >> a[i].fi;
    }

    for (int i = n; i >= 1; --i) {
        f[i] = 1;
        if (a[i].fi <= S) {
            if (a[i].se) {
                for (int j = 1; j <= a[i].fi; ++j) {
                    if (i + j * a[i].se > n) break;
                    add(f[i], f[i + j * a[i].se]);
                }
            }
        }
        else {
            if (a[i].se > S) {
                for (int j = 1; j <= a[i].fi; ++j) {
                    if (i + j * a[i].se > n) break;
                    add(f[i], f[i + j * a[i].se]);
                }
            }
            else {
                if (a[i].se) {
                    add(f[i], calc[i + a[i].se][a[i].se]);
                    sub(f[i], calc[min(n + 1, i + a[i].se * (a[i].fi + 1))][a[i].se]);
                }
            }
        }
        for (int d = 1; d <= S; ++d) {
            add(calc[i][d], f[i]);
            add(calc[i][d], calc[i + d][d]);
        }
        // cout << i << ' ' << f[i] << '\n';

    }

    cout << f[1];

    return;
}

int main() {

    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    #define TASK "task"
    if (fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }

    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
    }

    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:104:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  104 |         freopen(TASK".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:105:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  105 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 13 / 13
• Subtask 3: 16 / 16
• Subtask 4: 34 / 34
• Subtask 5: 29 / 29