oj.uz

Submission #217187

# Submission time Handle Problem Language Result Execution time Memory
217187 2020-03-29T08:01:20 Z combi1k1 Ruins 3 (JOI20_ruins3) C++14
100 / 100
 464 ms 3576 KB 
#include<bits/stdc++.h>

using namespace std;

#define ll  long long
#define ld  double

#define sz(x)   (int)x.size()
#define all(x)  x.begin(),x.end()

#define pb  emplace_back
#define X   first
#define Y   second

const int   N   = 1500;
const int   mod = 1e9 + 7;

void add(int &a,int b)  {
    a += b;
    if (a >= mod)
        a -= mod;
}
void sub(int &a,int b)  {
    a -= b;
    if (a <  0)
        a += mod;
}
int mul(int a,int b)    {
    return  1ll * a * b % mod;
}
int Pow(int a,int b)    {
    int ans = 1;
    while (b)   {
        if(b & 1)   ans = mul(ans,a);
        a = mul(a,a);   b >>= 1;
    }
    return  ans;
}
int inv(int a,int p)    {
    return  a == 1 ? 1 : p - 1ll * p * inv(p % a,a) / a;
}

typedef pair<int,int>   ii;

int Fac[N];
int Inv[N];

int Ckn(int n,int k)    {
    if (n < k)  return  0;
    if (k < 0)  return  0;

    return  mul(Fac[n],mul(Inv[k],Inv[n - k]));
}
int a[N];
int f[N][N];

int main()  {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    Fac[0] = Inv[0] = 1;

    for(int i = 1 ; i < N ; ++i)    Fac[i] = mul(Fac[i - 1],i);     Inv[N - 1] = inv(Fac[N - 1],mod);
    for(int i = N - 2 ; i ; --i)    Inv[i] = mul(Inv[i + 1],i + 1);

    int n;  cin >> n;

    for(int i = 0 ; i < n ; ++i)    cin >> a[i];

    f[0][0] = 1;

    for(int i = 0 ; i < n ; ++i)
    for(int j = 0 ; j <= n ; ++j)   if (f[i][j])
        for(int k = 0 ; k <= min(n,a[i] - i - 1) - j ; ++k) {
            int nxt = f[i][j];

            nxt = mul(nxt,Fac[k + k]);
            nxt = mul(nxt,Inv[k]);

            nxt = mul(nxt,Ckn(a[i] - i - j - 1,k));

            if(!k)  nxt = mul(nxt,j - i);

            add(f[i + 1][j + k],nxt);
        }

    int ans = f[n][n];

    for(int i = 0 ; i < n ; ++i)
        ans = mul(ans,500000004);

    cout << ans << endl;
}

Compilation message

ruins3.cpp: In function 'int main()':
ruins3.cpp:63:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
     for(int i = 1 ; i < N ; ++i)    Fac[i] = mul(Fac[i - 1],i);     Inv[N - 1] = inv(Fac[N - 1],mod);
     ^~~
ruins3.cpp:63:69: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
     for(int i = 1 ; i < N ; ++i)    Fac[i] = mul(Fac[i - 1],i);     Inv[N - 1] = inv(Fac[N - 1],mod);
                                                                     ^~~

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 384 KB Output is correct
2 Correct 4 ms 384 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Correct 4 ms 256 KB Output is correct
5 Correct 5 ms 384 KB Output is correct
6 Correct 4 ms 384 KB Output is correct
7 Correct 5 ms 384 KB Output is correct
8 Correct 5 ms 384 KB Output is correct
9 Correct 4 ms 384 KB Output is correct
10 Correct 5 ms 384 KB Output is correct

Subtask #2
52.0 / 52.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 384 KB Output is correct
2 Correct 4 ms 384 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Correct 4 ms 256 KB Output is correct
5 Correct 5 ms 384 KB Output is correct
6 Correct 4 ms 384 KB Output is correct
7 Correct 5 ms 384 KB Output is correct
8 Correct 5 ms 384 KB Output is correct
9 Correct 4 ms 384 KB Output is correct
10 Correct 5 ms 384 KB Output is correct
11 Correct 5 ms 640 KB Output is correct
12 Correct 5 ms 640 KB Output is correct
13 Correct 5 ms 640 KB Output is correct
14 Correct 5 ms 640 KB Output is correct
15 Correct 4 ms 384 KB Output is correct
16 Correct 5 ms 640 KB Output is correct
17 Correct 5 ms 384 KB Output is correct
18 Correct 5 ms 640 KB Output is correct
19 Correct 5 ms 640 KB Output is correct
20 Correct 5 ms 640 KB Output is correct

Subtask #3
42.0 / 42.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 384 KB Output is correct
2 Correct 4 ms 384 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Correct 4 ms 256 KB Output is correct
5 Correct 5 ms 384 KB Output is correct
6 Correct 4 ms 384 KB Output is correct
7 Correct 5 ms 384 KB Output is correct
8 Correct 5 ms 384 KB Output is correct
9 Correct 4 ms 384 KB Output is correct
10 Correct 5 ms 384 KB Output is correct
11 Correct 5 ms 640 KB Output is correct
12 Correct 5 ms 640 KB Output is correct
13 Correct 5 ms 640 KB Output is correct
14 Correct 5 ms 640 KB Output is correct
15 Correct 4 ms 384 KB Output is correct
16 Correct 5 ms 640 KB Output is correct
17 Correct 5 ms 384 KB Output is correct
18 Correct 5 ms 640 KB Output is correct
19 Correct 5 ms 640 KB Output is correct
20 Correct 5 ms 640 KB Output is correct
21 Correct 10 ms 2816 KB Output is correct
22 Correct 8 ms 2816 KB Output is correct
23 Correct 8 ms 2816 KB Output is correct
24 Correct 13 ms 2816 KB Output is correct
25 Correct 5 ms 384 KB Output is correct
26 Correct 5 ms 384 KB Output is correct
27 Correct 5 ms 384 KB Output is correct
28 Correct 6 ms 2816 KB Output is correct
29 Correct 5 ms 384 KB Output is correct
30 Correct 464 ms 3448 KB Output is correct
31 Correct 244 ms 3448 KB Output is correct
32 Correct 349 ms 3320 KB Output is correct
33 Correct 448 ms 3448 KB Output is correct
34 Correct 241 ms 3320 KB Output is correct
35 Correct 358 ms 3576 KB Output is correct
36 Correct 435 ms 3424 KB Output is correct