Submission #121236

#	Time	Username	Problem	Language	Result	Execution time	Memory
121236		BThero	Fibonacci representations (CEOI18_fib)	C++17	0 / 100	2 ms	384 KiB

fib

// Why am I so dumb? :c
// chrono::system_clock::now().time_since_epoch().count()

//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>

#define pb push_back
#define mp make_pair

#define all(x) (x).begin(), (x).end()

#define fi first
#define se second

using namespace std;
using namespace __gnu_pbds;

typedef long long ll;   
template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

const int MOD = (int)1e9 + 7;

int addMod(int a, int b, int m = MOD) {
    a += b;

    if (m <= a) {
        a -= m;
    }

    return a;
}

int mulMod(int a, int b, int m = MOD) {
    return a * 1ll * b % m;
}

int binPow(int a, int b) {
    int ret = 1;

    while (b > 0) {
        if (b & 1) {
            ret = mulMod(ret, a);
        }

        a = mulMod(a, a);
        b >>= 1;
    }

    return ret;
}

int n;

void solve() {
    scanf("%d", &n);
    int ans = 1;

    set<int> S;
    S.insert(0);

    for (int i = 1; i <= n; ++i) {
        int x;
        scanf("%d", &x);

        auto it = S.lower_bound(x);
        auto it2 = it;
        --it;      

        if (it2 != S.end()) {
            ans = mulMod(ans, binPow((*it2 - *it + 1) / 2, MOD - 2));
            ans = mulMod(ans, (*it2 - x + 1) / 2);
        }

        ans = mulMod(ans, (x - *it + 1) / 2);

        S.insert(x);        
        printf("%d\n", ans);
    }
}

int main() {
    int tt = 1;

    while (tt--) {
        solve();
    }

    return 0;
}

Compilation message (stderr)

fib.cpp: In function 'void solve()':
fib.cpp:59:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
fib.cpp:67:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &x);
         ~~~~~^~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 20
• Subtask 3: 0 / 15
• Subtask 4: 0 / 10
• Subtask 5: 0 / 15
• Subtask 6: 0 / 35