Submission #1033887

#	Time	Username	Problem	Language	Result	Execution time	Memory
1033887		trucmai	Trains (BOI24_trains)	C++17	71 / 100	172 ms	254560 KiB

Main

#include <bits/stdc++.h>
#ifdef LOCAL
#include "/home/trcmai/code/tools.h"
#define debug(x...)                                                           \
    cerr << "\e[91m" << __func__ << ":" << __LINE__ << " [" << #x << "] = ["; \
    _print(x);                                                                \
    cerr << "\e[39m" << endl;
#else
#define debug(x...)
#endif
using namespace std;
#define all(a) a.begin(), a.end()
#define fi first
#define se second
#define ll long long
#define endl '\n'
const int N = 1e5 + 6, LOG = 27, MOD = 1e9 + 7;
const ll INF = 1e18;
int n;

ll add(ll x, ll y) { return (x + y) % MOD; }
ll sub(ll x, ll y) { return (x - y % MOD + MOD) % MOD; }
ll mul(ll x, ll y) { return (x * y) % MOD; }
void upd(ll& x, ll y) { x = add(x, y); }
ll dp[N], d[N], x[N];
const int BS = 320;
ll sum[N][BS];
signed main()
{
    cin.tie(0)->sync_with_stdio(0);
    auto solver = [&]() {
        cin >> n;
        for (int i = 1; i <= n; ++i)
            cin >> d[i] >> x[i];
        for (int i = n; i >= 1; --i) {
            dp[i] = 1;
            if (d[i] > BS) {
                for (int j = 1; j <= x[i]; ++j) {
                    if (i + d[i] * j > n)
                        break;
                    upd(dp[i], dp[i + d[i]*j]);
                }
            }
            if (d[i] <= BS && d[i] > 0 && x[i] > 0) {
                upd(dp[i], sum[i + d[i]][d[i]]);
                if (i + (x[i] + 1) * d[i] <= n)
                    dp[i] = sub(dp[i], sum[i + (x[i] + 1) * d[i]][d[i]]);
            }
            for (int j = 1; j <= BS; ++j)
                sum[i][j] = add(sum[i + j][j], dp[i]);
        }
        cout << dp[1] << endl;
    };
    int t = 1; // cin>>t;
    while (t--)
        solver();
}

Compilation message (stderr)

Main.cpp: In lambda function:
Main.cpp:50:32: warning: iteration 319 invokes undefined behavior [-Waggressive-loop-optimizations]
   50 |                 sum[i][j] = add(sum[i + j][j], dp[i]);
      |                             ~~~^~~~~~~~~~~~~~~~~~~~~~
Main.cpp:49:31: note: within this loop
   49 |             for (int j = 1; j <= BS; ++j)
      |                             ~~^~~~~

• Subtask 1: 8 / 8
• Subtask 2: 13 / 13
• Subtask 3: 16 / 16
• Subtask 4: 34 / 34
• Subtask 5: 0 / 29