Submission #559559

#	Time	Username	Problem	Language	Result	Execution time	Memory
559559		Pherokung	Kangaroo (CEOI16_kangaroo)	C++14	0 / 100	0 ms	212 KiB

kangaroo

#include<bits/stdc++.h>
using namespace std;
#define N 2005
#define ll long long
const int mod = 1e9+7;
int n,cs,cf,del;
ll dp[N][N],ans;
int main(){
	scanf("%d%d%d",&n,&cs,&cf);
	
	dp[0][0] = 1;
	for(int idx=1;idx<=n;idx++){
		for(int comp=1;comp<=idx;comp++){
			if(idx == cs || idx == cf){
				dp[idx][comp] += dp[idx-1][comp];
				dp[idx][comp] += dp[idx-1][comp-1];
				del++;
			}
			else{
				if(comp * 2 - del > 0) dp[idx][comp] += dp[idx-1][comp] * (comp * 2 - del);
				if(comp - del > 0) dp[idx][comp] += dp[idx-1][comp-1] * (comp - del);	
				dp[idx][comp] += dp[idx-1][comp+1] * (comp);
			}
//			printf("?? %d %d : %lld\n",idx,comp,dp[idx][comp]);
			dp[idx][comp] %= mod;
		}
	}
	
	printf("%lld",dp[n][1]);
}

Compilation message (stderr)

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:9:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
    9 |  scanf("%d%d%d",&n,&cs,&cf);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 6
• Subtask 2: 0 / 30
• Subtask 3: 0 / 15
• Subtask 4: 0 / 49