Submission #1193904

#	Time	Username	Problem	Language	Result	Execution time	Memory
1193904		Sir_Ahmed_Imran	Kangaroo (CEOI16_kangaroo)	C++17	100 / 100	27 ms	31048 KiB

kangaroo

            //    01001100 01001111 01010100 01000001    \\
            //                                           \\
            //                ╦  ╔═╗╔╦╗╔═╗               \\
            //                ║  ║ ║ ║ ╠═╣               \\
            //                ╩═╝╚═╝ ╩ ╩ ╩               \\
            //                                           \\
            //    01001100 01001111 01010100 01000001    \\

#include <bits/stdc++.h>
using namespace std;
#define N 2001
#define nl '\n'
#define ff first
#define ss second
#define add insert
#define ll long long
#define ld long double
#define terminator main
#define pll pair<ll,ll>
#define append push_back
#define pii pair<int,int>
#define all(x) (x).begin(),(x).end()
#define L0TA ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)

const int M = 1e9 + 7;

int add(int x, int y){
    return (x + y) % M;
}

int mul(int x, int y){
    return (1ll * x * y) % M;
}

int dp[N][N][3];

void solve(){
    int n, s, e, t;
    cin >> n >> s >> e;
    t = (s == 1) + (e == 1);
    dp[1][1][t] = 1;
    for(int i = 2; i <= n; i++){
        for(int j = 1; j < i; j++){
            if(s == i || e == i){
                dp[i][j][t + 1] = add(dp[i][j][t + 1], dp[i - 1][j][t]);
                dp[i][j + 1][t + 1] = add(dp[i][j + 1][t + 1], dp[i - 1][j][t]);
            }
            else{
                dp[i][j - 1][t] = add(dp[i][j - 1][t], mul(dp[i - 1][j][t], j - 1));
                dp[i][j + 1][t] = add(dp[i][j + 1][t], mul(dp[i - 1][j][t], j + 1 - t));
            }
        }
        t += (s == i || e == i);
    }
    cout << dp[n][1][2];
}

int terminator(){
    L0TA;
    solve();
    return 0;
}

• Subtask 1: 6 / 6
• Subtask 2: 30 / 30
• Subtask 3: 15 / 15
• Subtask 4: 49 / 49