题解 | #兔子的序列#

#include <iostream>
#include <vector>
#include <cmath> // For sqrt() function

using namespace std;

bool isPerfectSquare(int num) {
    int root = static_cast<int>(sqrt(num));
    return root * root == num;
}

int main() {
    int n;
    cin >> n;
    
    vector<int> arr(n);
    for (int i = 0; i < n; ++i) {
        cin >> arr[i];
    }
    
    int maxNonSquare = -1;
    for (int i = 0; i < n; ++i) {
        if (!isPerfectSquare(arr[i])) {
            if (arr[i] > maxNonSquare) {
                maxNonSquare = arr[i];
            }
        }
    }
    
    cout << maxNonSquare << endl;

    return 0;
}