Submission #15212

#	Time	Username	Problem	Language	Result	Execution time	Memory
15212		hodduc	맛있는 과자 (kriii3_A)	C++98	33 / 33	0 ms	1216 KiB

A

#include<stdio.h>
#include<cmath>
#include<algorithm>

int a,b,n;
long long k;
long long pyt[50][50];
double base, lna, lnb, lnc;

struct L {
        double val;
        long long cnt;
}ll[50];

bool acomp(L a, L b) {
        return a.val < b.val;
}

int main()
{
        pyt[0][0] = 1;
        for(int i=1;i<41;i++){
                pyt[i][0]=1;
                pyt[i][i]=1;
                for(int j=1;j<i;j++) pyt[i][j]=pyt[i-1][j]+pyt[i-1][j-1];
        }

        scanf("%d %d %d %lld", &a, &b, &n, &k);
        lna = log(a)*2;
        lnb = log(b)*2;
        lnc = log(a*a+b*b);
        base = log(a*b) - log(2) - n*lnc;

        long long tmp = 1; tmp <<= n;
        k = tmp + 1 - k;

        for(int i = 0; i <= n; i++)
        {
                ll[i].val = lna*i + lnb*(n-i);
                ll[i].cnt = pyt[n][i];
        }

        int L = n+1;

        std::sort(ll, ll+L, acomp);
        long long v = 0;
//      for(int i = 0; i < L; i++){
//              printf("%lld %.12lf\n", ll[i].cnt, ll[i].val+base);
//      }
        for(int i = 0; i < L; i++){
                v += ll[i].cnt;
                if (v >= k){
                        printf("%.12lf\n", ll[i].val+base);
                        break;
                }
        }

        return 0;
}

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