Submission #67216

#	Time	Username	Problem	Language	Result	Execution time	Memory
67216		Googal	Kangaroo (CEOI16_kangaroo)	C++14	100 / 100	80 ms	23808 KiB

kangaroo

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int NMAX = 2 * 1e3 + 1e2;
const ll MOD = 1e9 + 7;

ll n, st, fn;
ll res;
ll dp[NMAX][NMAX];

int main()
{
    ios::sync_with_stdio(false);
	cin >> n >> st >> fn;

	dp[0][0] = 1;

	for(ll i = 1; i < n; i++) {
      if(i == st || i == fn) {
        for(int j = 0; j < i; j++)
          (dp[i][j] += dp[i - 1][j]) %= MOD;
        for(int j = 1; j < i; j++)
          (dp[i][j - 1] += dp[i - 1][j] * j % MOD) %= MOD;
          continue;
      }

      for(ll j = 0; j < i; j++) {
        if(j >= 2){
          (dp[i][j - 1] += dp[i - 1][j] * j % MOD * (j - 1) % MOD) %= MOD;
        }

        if(i >= st){
          (dp[i][j - 1] += dp[i - 1][j] * j % MOD) %= MOD;
        }

        if(i >= fn){
          (dp[i][j - 1] += dp[i - 1][j] * j % MOD) %= MOD;
        }

        (dp[i][j + 1] += dp[i - 1][j]) %= MOD;
      }
	}

	cout << dp[n - 1][0] << '\n';

	return 0;
}

Compilation message (stderr)

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:25:9: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
         for(int j = 1; j < i; j++)
         ^~~
kangaroo.cpp:27:11: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
           continue;
           ^~~~~~~~

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