Submission #15816

#	Time	Username	Problem	Language	Result	Execution time	Memory
15816		jihoon	맛있는 과자 (kriii3_A)	C++98	33 / 33	0 ms	1204 KiB

A

#include<cstdio>
#include<cmath>
long long int ncr[41][41];
int main(){
	int a,b,n,t;
	double lna,lnb,lnn;
	long long int k,sum=0;
	scanf("%d %d %d %lld",&a,&b,&n,&k);
	//printf("%d %d %d %lld\n",a,b,n,k);
	ncr[0][0]=1;
	if(a>b){
		t=a;a=b;b=t;
	}
	t=a*a+b*b;
	lna=log((a*a)/(double)t);
	lnb=log((b*b)/(double)t);
	lnn=log(a*b/2.0);
	for(int i=1;i<=n;i++){
		ncr[i][0]=1;
		for(int j=1;j<=i;j++){
			ncr[i][j]=ncr[i-1][j-1]+ncr[i-1][j];
		}
	}
	for(int i=0;i<=n;i++){
		sum+=ncr[n][i];
		//printf("%d %lld %lld\n",i,sum,k);
		if(sum>=k){
			printf("%.12f",i*lna+(n-i)*lnb+lnn);
			return 0;
		}
	}
}

• Subtask 1: 10 / 10
• Subtask 2: 23 / 23