NC14733 is a complete square number

There are two ways to ask this question: spelling and math
Let’s talk about math practice:
Since the number of square digits is a continuous number, we open the root number in the range, move to the integer area in the middle, and then determine the length.
Here is the colon method:
We can store all square numbers first, and then find the two search elements in the left and right intervals. Use low_bound and overbound

Math: SQRT®-SQRT(L) +1
2 items: overbound(a, a + n, r) – down_bound (a, a + n, l)

Math method:

#include<iostream>
#include<cmath>
using namespace std;
 
int main() {
    int T;cin >> T;
    while (T--) {
        int l, r;cin >> l >> r;
        cout << floor(sqrt(1.0 * r)) - ceil(sqrt(1.0 * l)) + 1 << endl;
    }
    return 0;
}

Then there are two points:

#include<iostream>
#include<cmath>
#include<algorithm>
using namespace std;
const int maxn = 1e5 + 5;

int a[maxn];

int main() {
	int len = 0;
	for (int i = 0;i * i <= 1e9;i++)
		a[len++] = i * i;
	int T;cin >> T;
	while (T--) {
		int l, r;
		cin >> l >> r;
		cout << upper_bound(a, a + len, r) - lower_bound(a, a + len, l) << endl;
	}
	return 0;
}