Submission #530518

#	Time	Username	Problem	Language	Result	Execution time	Memory
530518		Killer2501	Asceticism (JOI18_asceticism)	C++14	100 / 100	12 ms	6604 KiB

asceticism

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define ull unsigned long long
#define pb push_back
#define pll pair<ll, ll>
#define pii pair<int, int>
#define fi first
#define se second
using namespace std;
const int N = 1e5+5;
const int M = 1e2+2;
const int mod = 1e9+7;
const ll base = 75;
const int inf = 1e9;
int m, n, t, b[N], d[N], lab[N], q;
int k, a[N], dp[N];
ll ans, tong;
vector<int> adj[N];
vector<pii> vi;
string s[N];
bool vis[N];
ll pw(ll k, ll n)
{
    ll total = 1;
    for(; n; n >>= 1)
    {
        if(n&1)total = total * k % mod;
        k = k * k % mod;
    }
    return total;
}
void add(int &x, int y)
{
    x += y;
    if(x >= mod)x -= mod;
}
int findp(int u)
{
    return lab[u] < 0 ? u : lab[u] = findp(lab[u]);
}
void hop(int u, int v)
{
    u = findp(u);
    v = findp(v);
    if(u == v)return;
    if(lab[u] > lab[v])swap(u, v);
    lab[u] += lab[v];
    lab[v] = u;
}
int C(int u, int v)
{
    if(u > v)return 0;
    return 1ll * a[v] * b[u] % mod * b[v-u] % mod;
}
void sol()
{
    cin >> n >> k;
    a[0] = b[0] = 1;
    for(int i = 1; i <= n+1; i ++)
        a[i] = 1ll * a[i-1] * i % mod;
    b[n+1] = pw(a[n+1], mod-2);
    for(int i = n; i > 0; i --)b[i] = 1ll * b[i+1] * (i+1) % mod;
    for(int i = 0; i <= k; i ++)
    {
        tong = 1ll*pw(k-i, n) * C(i, n+1) % mod;
        if(i&1)ans = (ans -  tong + mod) % mod;
        else ans = (ans + tong) % mod;
        //cout << i <<" "<<tong<<'\n';
    }
    cout << ans;
}
int main()
{
    cin.tie(0);
    cout.tie(0);
    ios_base::sync_with_stdio(0);
    #define task "test"
    if(fopen(task".inp", "r"))
	{
		freopen(task".inp", "r", stdin);
		freopen(task".out", "w", stdout);
	}
    int test = 1;
    //cin >> test;
    while(test -- > 0)sol();
    return 0;
}

Compilation message (stderr)

asceticism.cpp: In function 'int main()':
asceticism.cpp:81:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   81 |   freopen(task".inp", "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
asceticism.cpp:82:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   82 |   freopen(task".out", "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 20 / 20
• Subtask 3: 25 / 25
• Subtask 4: 51 / 51