oj.uz

Submission #1116924

# Submission time Handle Problem Language Result Execution time Memory
1116924 2024-11-22T15:11:50 Z byebye75 Ruins 3 (JOI20_ruins3) C++14
100 / 100
 314 ms 8948 KB 
#include <bits/stdc++.h>
using namespace std;
 
const int MOD = 1e9 + 7;
 
int n;
int a[1205];
int dp[1205][1205], C[1205][1205];
int fact[1205];
 
void build_pascal(){
    fact[0] = 1;
    for(int i = 1; i <= 1200 ; ++i) fact[i] = (1LL * fact[i - 1] * i) % MOD;
 
    C[0][0] = 1;
    for(int i = 1; i <= 1200 ; ++i){
        C[i][0] = 1;
        for(int j = 1; j <= i ; ++j){
            C[i][j] = C[i - 1][j] + C[i - 1][j - 1];
            if(C[i][j] >= MOD) C[i][j] -= MOD;
        }
    }
}
 
inline int lgput(int x, int p){
    int ans = 1, aux = x;
    for(int i = 1; i <= p ; i = i << 1){
        if(i & p) ans = (1LL * ans * aux) % MOD;
        aux = (1LL * aux * aux) % MOD;
    }
    return ans;
}
 
int main()
{
//    freopen("1.in", "r", stdin);
 
    scanf("%d", &n);
    for(int i = 1; i <= n ; ++i)
        scanf("%d", &a[i]);
 
    if(a[1] == 1 || a[n] != 2 * n){
        printf("0");
        return 0;
    }
 
    build_pascal();
 
    dp[0][n + 1] = 1;
    for(int l = 1, i = 0; i < n ; ++i, l = 1 - l){
        for(int j = n + 1; j >= 1 ; --j){
            if(dp[i][j] == 0) continue ;
 
            int libere = a[i + 1] - (i + 1) - (n - j + 1);
            for(int k = 0; k <= min(n, min(libere, j)) ; ++k){
                if(j - k > n - i) continue ;
                int pos = 1;
                if(k == 0) pos = (n - (j - k) + 1) * 2 - (a[i + 1] - (libere - k) - 1);
 
                int add = 1LL * dp[i][j] * C[2 * k][k] % MOD * C[libere][k] % MOD * fact[k] % MOD;
                add = 1LL * add * pos % MOD;
                dp[i + 1][j - k] = (dp[i + 1][j - k] + add);
                if(dp[i + 1][j - k] >= MOD) dp[i + 1][j - k] -= MOD;
            }
        }
    }
 
    int Sol = dp[n][1];
    for(int i = 1; i <= n ; ++i) Sol = (1LL * Sol * lgput(2, MOD - 2)) % MOD;
 
    printf("%d", Sol);
 
    return 0;
}

Compilation message

ruins3.cpp: In function 'int main()':
ruins3.cpp:38:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
ruins3.cpp:40:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |         scanf("%d", &a[i]);
      |         ~~~~~^~~~~~~~~~~~~

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 6736 KB Output is correct
2 Correct 4 ms 6764 KB Output is correct
3 Correct 4 ms 6736 KB Output is correct
4 Correct 1 ms 436 KB Output is correct
5 Correct 4 ms 6736 KB Output is correct
6 Correct 4 ms 6904 KB Output is correct
7 Correct 1 ms 336 KB Output is correct
8 Correct 4 ms 6736 KB Output is correct
9 Correct 4 ms 6736 KB Output is correct
10 Correct 4 ms 6736 KB Output is correct

Subtask #2
52.0 / 52.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 6736 KB Output is correct
2 Correct 4 ms 6764 KB Output is correct
3 Correct 4 ms 6736 KB Output is correct
4 Correct 1 ms 436 KB Output is correct
5 Correct 4 ms 6736 KB Output is correct
6 Correct 4 ms 6904 KB Output is correct
7 Correct 1 ms 336 KB Output is correct
8 Correct 4 ms 6736 KB Output is correct
9 Correct 4 ms 6736 KB Output is correct
10 Correct 4 ms 6736 KB Output is correct
11 Correct 5 ms 6904 KB Output is correct
12 Correct 4 ms 6736 KB Output is correct
13 Correct 4 ms 6596 KB Output is correct
14 Correct 1 ms 336 KB Output is correct
15 Correct 1 ms 336 KB Output is correct
16 Correct 4 ms 6736 KB Output is correct
17 Correct 1 ms 336 KB Output is correct
18 Correct 4 ms 6736 KB Output is correct
19 Correct 4 ms 6736 KB Output is correct
20 Correct 5 ms 6736 KB Output is correct

Subtask #3
42.0 / 42.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 6736 KB Output is correct
2 Correct 4 ms 6764 KB Output is correct
3 Correct 4 ms 6736 KB Output is correct
4 Correct 1 ms 436 KB Output is correct
5 Correct 4 ms 6736 KB Output is correct
6 Correct 4 ms 6904 KB Output is correct
7 Correct 1 ms 336 KB Output is correct
8 Correct 4 ms 6736 KB Output is correct
9 Correct 4 ms 6736 KB Output is correct
10 Correct 4 ms 6736 KB Output is correct
11 Correct 5 ms 6904 KB Output is correct
12 Correct 4 ms 6736 KB Output is correct
13 Correct 4 ms 6596 KB Output is correct
14 Correct 1 ms 336 KB Output is correct
15 Correct 1 ms 336 KB Output is correct
16 Correct 4 ms 6736 KB Output is correct
17 Correct 1 ms 336 KB Output is correct
18 Correct 4 ms 6736 KB Output is correct
19 Correct 4 ms 6736 KB Output is correct
20 Correct 5 ms 6736 KB Output is correct
21 Correct 9 ms 8948 KB Output is correct
22 Correct 6 ms 8528 KB Output is correct
23 Correct 8 ms 8628 KB Output is correct
24 Correct 9 ms 8528 KB Output is correct
25 Correct 1 ms 336 KB Output is correct
26 Correct 4 ms 6736 KB Output is correct
27 Correct 1 ms 504 KB Output is correct
28 Correct 6 ms 8528 KB Output is correct
29 Correct 2 ms 336 KB Output is correct
30 Correct 314 ms 8796 KB Output is correct
31 Correct 160 ms 8776 KB Output is correct
32 Correct 228 ms 8776 KB Output is correct
33 Correct 294 ms 8792 KB Output is correct
34 Correct 162 ms 8788 KB Output is correct
35 Correct 231 ms 8776 KB Output is correct
36 Correct 307 ms 8804 KB Output is correct