解法一、公式解

✅ 完整代碼

評分結果(參考) ： AC (3ms, 340KB)

#include <bits/stdc++.h>
using namespace std;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int a, b, c;
    cin >> a >> b >> c;

    int b2_4ac = b*b - 4*a*c;

    if(b2_4ac > 0){
        cout << "Two different roots x1=" <<  (-b + sqrt(b2_4ac))/2/a 
                            << " , x2=" << (-b - sqrt(b2_4ac))/2/a;
    }
    else if(b2_4ac == 0){
        cout << "Two same roots x=" << (-b)/2/a;
    }
    else{
        cout << "No real root";
    }

    return 0;
}