T3代码哪里错了？

#include <bits/stdc++.h>
using namespace std;
int main()
{
	unsigned long long n;
	cin >> n;
	for (unsigned long long i = min((unsigned long long)(cbrt(n)), (unsigned long long)110011); ; i--) {
		string a = to_string(i * i * i);
		string b = a;
		reverse(a.begin(), a.end());
		if (a == b) {
			cout << i * i * i;
			return 0;
		}
	}
	cout << 1;
	return 0;
}

改成这样就对了：

#include <bits/stdc++.h>
using namespace std;
int main()
{
	unsigned long long n;
	cin >> n;
	for (unsigned long long i = min((unsigned long long)(sqrt(n)), (unsigned long long)110011); ; i--) {
		if (i * i * i > n)
			continue;
		string a = to_string(i * i * i);
		string b = a;
		reverse(a.begin(), a.end());
		if (a == b) {
			cout << i * i * i;
			return 0;
		}
	}
	cout << 1;
	return 0;
}