Submission #5395660

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Source Code Expand

#include <bits/stdc++.h>
#define fi first
#define se second
#define pii pair<int,int>
#define mp make_pair
#define pb push_back
#define space putchar(' ')
#define enter putchar('\n')
#define eps 1e-10
#define MAXN 1000005
//#define ivorysi
using namespace std;
typedef long long int64;
typedef unsigned int u32;
typedef double db;
template<class T>
void read(T &res) {
    res = 0;T f = 1;char c = getchar();
    while(c < '0' || c > '9') {
	if(c == '-') f = -1;
	c = getchar();
    }
    while(c >= '0' && c <= '9') {
	res = res * 10 +c - '0';
	c = getchar();
    }
    res *= f;
}
template<class T>
void out(T x) {
    if(x < 0) {x = -x;putchar('-');}
    if(x >= 10) {
	out(x / 10);
    }
    putchar('0' + x % 10);
}
int64 N,A;

void Solve() {
    read(N);read(A);
    int64 ans = N;
    for(int i = 2 ; i <= 40 ; ++i) {
	if((1LL << i) > N) break;
	int64 tmp = (i - 1) * A;
	int64 l = 1,r = N;
	while(l < r) {
	    int64 mid = (l + r + 1) >> 1;
	    int64 t = 1;
	    bool f = 1;
	    for(int j = 1 ; j <= i ; ++j) {
		if(mid > N / t) {f = 0;break;}
		t = t * mid;
	    }
	    if(f) l = mid;
	    else r = mid - 1;
	}
	int64 t = 1;
	for(int j = 1 ; j <= i ; ++j) {
	    t = t * l;
	}
	int64 cnt = l * i;
	while(t < N) {
	    t /= l;
	    if((l + 1) <= N / t) {t = t * (l + 1); ++cnt;}
	    else {++cnt;break;}
	}
	ans = min(ans,tmp + cnt);
    }
    out(ans);enter;
}
int main() {
#ifdef ivorysi
    freopen("f1.in","r",stdin);
#endif
    Solve();
    return 0;
}

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