This documentation is automatically generated by online-judge-tools/verification-helper
#include "nt/integer_kth_root.hpp"
u64 integer_kth_root(u64 k, u64 a) {
assert(k >= 1);
if (a == 0 || a == 1 || k == 1) return a;
if (k >= 64) return 1;
if (k == 2) return sqrtl(a);
if (a == u64(-1)) --a;
struct S {
u64 v;
S& operator*=(const S& o) {
v = v <= u64(-1) / o.v ? v * o.v : u64(-1);
return *this;
}
};
auto power = [&](S x, ll n) -> S {
S v{1};
while (n) {
if (n & 1) v *= x;
x *= x;
n /= 2;
}
return v;
};
u64 res = pow(a, nextafter(1 / double(k), 0));
while (power(S{res + 1}, k).v <= a) ++res;
return res;
}
#line 1 "nt/integer_kth_root.hpp"
u64 integer_kth_root(u64 k, u64 a) {
assert(k >= 1);
if (a == 0 || a == 1 || k == 1) return a;
if (k >= 64) return 1;
if (k == 2) return sqrtl(a);
if (a == u64(-1)) --a;
struct S {
u64 v;
S& operator*=(const S& o) {
v = v <= u64(-1) / o.v ? v * o.v : u64(-1);
return *this;
}
};
auto power = [&](S x, ll n) -> S {
S v{1};
while (n) {
if (n & 1) v *= x;
x *= x;
n /= 2;
}
return v;
};
u64 res = pow(a, nextafter(1 / double(k), 0));
while (power(S{res + 1}, k).v <= a) ++res;
return res;
}