Submission #506391

#	Time	Username	Problem	Language	Result	Execution time	Memory
506391		RambaXGorilla	Kangaroo (CEOI16_kangaroo)	C++17	100 / 100	30 ms	16212 KiB

kangaroo

#include<cstdio>
#include<cstring>
using namespace std;
typedef long long ll;
const int modNum = 1000000007;
int N, S, F;
int dp[2010][2010];
int recur(int num, int comps){
    if(!comps){
        return 0;
    }
    if(num == 1){
        return comps == 1 ? 1 : 0;
    }
    if(dp[num][comps] + 1){
        return dp[num][comps];
    }
    if(num == S || num == F){
        dp[num][comps] = (recur(num - 1, comps - 1) + recur(num - 1, comps)) % modNum;
    }
    else{
        dp[num][comps] = ((ll) recur(num - 1, comps - 1) * (comps - (num > S) - (num > F)) + (ll) recur(num - 1, comps + 1) * comps) % modNum;
    }
    return dp[num][comps];
}
int main(){
    scanf("%d%d%d",&N,&S,&F);
    memset(dp, -1, sizeof(dp));
    printf("%d",recur(N, 1));
}

Compilation message (stderr)

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:27:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |     scanf("%d%d%d",&N,&S,&F);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~

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