Task: | Torni |
Sender: | mangolassi |
Submission time: | 2020-09-26 16:57:24 +0300 |
Language: | C++ (C++11) |
Status: | READY |
Result: | 100 |
group | verdict | score |
---|---|---|
#1 | ACCEPTED | 15 |
#2 | ACCEPTED | 41 |
#3 | ACCEPTED | 44 |
test | verdict | time | group | |
---|---|---|---|---|
#1 | ACCEPTED | 0.03 s | 1, 2, 3 | details |
#2 | ACCEPTED | 0.03 s | 2, 3 | details |
#3 | ACCEPTED | 0.03 s | 3 | details |
Code
#include <bits/stdc++.h>using namespace std;using ll = long long;const ll MOD = (ll)1e9 + 7;ll modPow(ll a, ll b) {if (b & 1) return a * modPow(a, b-1) % MOD;if (b == 0) return 1;return modPow(a*a % MOD, b / 2);}const int N = 1e6;ll pref1[N+1]; // Count if starts with two 1-wide piecesll pref2[N+1]; // Count if starts with one 2-wide piecell ans[N+1];void solve() {int n;cin >> n;cout << ans[n] << '\n';}int main() {ios_base::sync_with_stdio(false);cin.tie(0);// DP1[n] = \sum_{i = 1}^{n} (2^{i} DP1[n-i] + 2^{i-1} DP2[n-i])// DP2[n] = \sum_{i = 1}^{n} DP1[n-i] + DP2[n-i]ll two_inv = modPow(2, MOD - 2);ll two_pow = 2, inv_pow = two_inv;pref1[0] = two_inv;pref2[0] = 1;ans[0] = 1;for (int i = 1; i <= N; ++i) {ll dp1 = (two_pow * pref1[i-1]) % MOD;ll dp2 = pref2[i-1];ll nxt_inv_pow = (inv_pow * two_inv) % MOD;pref1[i] = (pref1[i-1] + inv_pow * dp1 + nxt_inv_pow * dp2) % MOD;pref2[i] = (pref2[i-1] + dp1 + dp2) % MOD;ans[i] = (dp1 + dp2) % MOD;two_pow = (2 * two_pow) % MOD;inv_pow = nxt_inv_pow;}int t;cin >> t;for (int ti = 0; ti < t; ++ti) solve();}
Test details
Test 1
Group: 1, 2, 3
Verdict: ACCEPTED
input |
---|
10 1 2 3 4 ... |
correct output |
---|
2 8 34 148 650 ... |
user output |
---|
2 8 34 148 650 ... |
Test 2
Group: 2, 3
Verdict: ACCEPTED
input |
---|
100 1 2 3 4 ... |
correct output |
---|
2 8 34 148 650 ... |
user output |
---|
2 8 34 148 650 ... Truncated |
Test 3
Group: 3
Verdict: ACCEPTED
input |
---|
100 996306 650655 896240 821967 ... |
correct output |
---|
87350005 606189151 122595036 193572715 227926807 ... |
user output |
---|
87350005 606189151 122595036 193572715 227926807 ... Truncated |