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Submission #988598

# Submission time Handle Problem Language Result Execution time Memory
988598 2024-05-25T08:57:34 Z steveonalex Kangaroo (CEOI16_kangaroo) C++17
100 / 100
 20 ms 16472 KB 
#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
 
#define MASK(i) (1ULL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
 
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
 
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
 
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
 
template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b) {a = b; return true;}
        return false;
    }
 
template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b) {a = b; return true;}
        return false;
    }
 
template <class T>
    void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
        for(auto item: container) out << item << separator;
        out << finish;
    }
 
template <class T>
    void remove_dup(vector<T> &a){
        sort(ALL(a));
        a.resize(unique(ALL(a)) - a.begin());
    }

const int N = 2007;
const int MOD = 1e9 + 7;

void add(int &a, int b){
    a += b;
    if (a >= MOD) a -= MOD;
}

int n, s, f; 
int dp[N][N];

namespace Odd{
    void solve(){
        int ans=  0;
        s--; f--;
        for(int iteration = 0; iteration <= 1; ++iteration){
            if (s != n-1 && f != n-1){
                memset(dp, 0, sizeof dp);
                dp[0][0] = 1;
                for(int i = 0; i<n-1; ++i) {
                    if (i == s || i == f){
                        for(int j = 0; j< n; ++j) add(dp[i+1][j], dp[i][j]);
                        continue;
                    }
                    int edge_cnt = (i >= s) + (i >= f);
                    for(int j = 0; j< n; ++j) if (dp[i][j]){
                        add(dp[i+1][j+1], dp[i][j]);
                        if (j > 0 && j + edge_cnt > 1){
                            int mul = j * (j-1) + edge_cnt * j;
                            add(dp[i+1][j-1], 1LL * mul * dp[i][j] % MOD);
                        }
                    }
                }
                add(ans, dp[n-1][0]);
            }

            s = n-1-s, f = n-1-f;
        }

        cout << ans << "\n";

        exit(0);
    }
}

namespace Even{
    void solve(){
        int ans = 0;
        s--; f--;
        for(int iteration = 0; iteration <= 1; ++iteration){
            if (s != n-1 && f != 0){
                memset(dp, 0, sizeof dp);
                dp[0][0] = 1;
                for(int i = 0; i<n; ++i) {
                    if (i == s){
                        for(int j = 0; j< n; ++j) add(dp[i+1][j], dp[i][j]);
                        continue;
                    }
                    if (i == f){
                        for(int j = 1; j<n; ++j) if (dp[i][j]){
                            add(dp[i+1][j-1], 1LL * dp[i][j] * j % MOD);
                        }
                        continue;
                    }
                    int edge_cnt = (i >= s) + (i >= f);
                    for(int j = 0; j< n; ++j) if (dp[i][j]){
                        add(dp[i+1][j+1], dp[i][j]);
                        if (j > 0 && j + edge_cnt > 1){
                            int mul = j * (j-1) + edge_cnt * j;
                            add(dp[i+1][j-1], 1LL * mul * dp[i][j] % MOD);
                        }
                    }
                }
                add(ans, dp[n-1][0]);
            }

            s = n-1-s, f = n-1-f;
        }

        cout << ans << "\n";

        exit(0);
    }
}

int main(void){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    
    cin >> n >> s >> f;
    if (n % 2 == 1) Odd::solve();
    else Even::solve();


    return 0;
}

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 16220 KB Output is correct
2 Correct 5 ms 16220 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 16220 KB Output is correct
2 Correct 5 ms 16220 KB Output is correct
3 Correct 3 ms 16472 KB Output is correct
4 Correct 5 ms 16220 KB Output is correct
5 Correct 4 ms 16012 KB Output is correct
6 Correct 5 ms 16220 KB Output is correct
7 Correct 5 ms 16220 KB Output is correct
8 Correct 5 ms 16220 KB Output is correct
9 Correct 5 ms 16216 KB Output is correct
10 Correct 6 ms 16220 KB Output is correct
11 Correct 6 ms 16220 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 16220 KB Output is correct
2 Correct 5 ms 16220 KB Output is correct
3 Correct 3 ms 16472 KB Output is correct
4 Correct 5 ms 16220 KB Output is correct
5 Correct 4 ms 16012 KB Output is correct
6 Correct 5 ms 16220 KB Output is correct
7 Correct 5 ms 16220 KB Output is correct
8 Correct 5 ms 16220 KB Output is correct
9 Correct 5 ms 16216 KB Output is correct
10 Correct 6 ms 16220 KB Output is correct
11 Correct 6 ms 16220 KB Output is correct
12 Correct 5 ms 16216 KB Output is correct
13 Correct 5 ms 16220 KB Output is correct
14 Correct 5 ms 16048 KB Output is correct
15 Correct 6 ms 16220 KB Output is correct
16 Correct 4 ms 16220 KB Output is correct
17 Correct 4 ms 16220 KB Output is correct
18 Correct 4 ms 16220 KB Output is correct
19 Correct 6 ms 15960 KB Output is correct
20 Correct 5 ms 16012 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 16220 KB Output is correct
2 Correct 5 ms 16220 KB Output is correct
3 Correct 3 ms 16472 KB Output is correct
4 Correct 5 ms 16220 KB Output is correct
5 Correct 4 ms 16012 KB Output is correct
6 Correct 5 ms 16220 KB Output is correct
7 Correct 5 ms 16220 KB Output is correct
8 Correct 5 ms 16220 KB Output is correct
9 Correct 5 ms 16216 KB Output is correct
10 Correct 6 ms 16220 KB Output is correct
11 Correct 6 ms 16220 KB Output is correct
12 Correct 5 ms 16216 KB Output is correct
13 Correct 5 ms 16220 KB Output is correct
14 Correct 5 ms 16048 KB Output is correct
15 Correct 6 ms 16220 KB Output is correct
16 Correct 4 ms 16220 KB Output is correct
17 Correct 4 ms 16220 KB Output is correct
18 Correct 4 ms 16220 KB Output is correct
19 Correct 6 ms 15960 KB Output is correct
20 Correct 5 ms 16012 KB Output is correct
21 Correct 6 ms 16220 KB Output is correct
22 Correct 6 ms 16220 KB Output is correct
23 Correct 7 ms 16224 KB Output is correct
24 Correct 20 ms 16216 KB Output is correct
25 Correct 20 ms 16220 KB Output is correct
26 Correct 17 ms 16216 KB Output is correct
27 Correct 15 ms 15988 KB Output is correct
28 Correct 12 ms 16220 KB Output is correct