Submission #683428

#	Time	Username	Problem	Language	Result	Execution time	Memory
683428		lam	Kangaroo (CEOI16_kangaroo)	C++14	100 / 100	20 ms	22984 KiB

kangaroo

#include <bits/stdc++.h>
#define int long long
using namespace std;
const int mod = 1e9 + 7;
const int maxn = 2010;
int n,s,f;
int dp[maxn][maxn];
signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);
    cin>>n>>s>>f;
    dp[0][0]=1LL;
    for (int i=1; i<=n; i++)
        for (int j=1; j<=i; j++)
    {
        if (i==s)
        {
            dp[i][j]=(dp[i-1][j] + dp[i-1][j-1])%mod;
        }
        else if (i==f)
        {
            dp[i][j]=(dp[i-1][j] + dp[i-1][j-1])%mod;
        }
        else
        {
            dp[i][j]=(j) * dp[i-1][j+1]%mod;
            int val = j-2;
            if (i<s) val++; if (i<f) val++;
            dp[i][j] = (dp[i][j] + val*dp[i-1][j-1]%mod)%mod;
        }
    }
    cout<<dp[n][1]<<'\n';
}

Compilation message (stderr)

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:29:13: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   29 |             if (i<s) val++; if (i<f) val++;
      |             ^~
kangaroo.cpp:29:29: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   29 |             if (i<s) val++; if (i<f) val++;
      |                             ^~

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