PTA 乙级 1063 计算谱半径 (20分) C++

 好说好说，水水水

#include<iostream>
#include<cmath>

using namespace std;

int main() {
    int n = 0;
    double r;
    cin >> n;
    for (int i = 0; i < n; ++i) {
        int a = 0, b = 0;
        double tmp = 0;
        cin >> a >> b;
        if (i == 0) r = sqrt(pow(a, 2) + pow(b, 2));
        else tmp = sqrt(pow(a, 2) + pow(b, 2));
        if (tmp > r) r = tmp;
    }
    printf("%.2f", r);
    return 0;
}