蓝桥杯 ALGO-160 算法训练 P0104

求方程ax2+bx+c=0的实数根。a, b, c由键盘输入, a!=0。若只有一个实数根（b2-4ac=0）则只输出x1，若无实数根（b2-4ac<0）则输出Error。
输入
2.5 7.5 1.0
输出
（注意等号前面后面都有一个空格）
x1 = -0.139853
x2 = -2.860147

#include <iostream>
#include <cmath>
using namespace std;
int main() {
    double a , b, c;
    cin >> a >> b >> c;
    double det = b * b - 4 * a * c;
    if(det < 0) {
        printf("%s","Error\n");
    }else if(det == 0 ) {
        printf("x1 = %6f\n",-1 * b / (2 * a));
    }else {
        printf("x1 = %6f\n",(-1 * b + sqrt(det)) / (2 * a));
        printf("x2 = %6f\n",(-1 * b - sqrt(det)) / (2 * a));
    }
    return 0;
}

#include <iostream>

#include <cmath>

using namespace std;

int main() {

double a , b, c;

cin >> a >> b >> c;

double det = b * b - 4 * a * c;

if(det < 0) {

printf("%s","Error\n");

}else if(det == 0 ) {

printf("x1 = %6f\n",-1 * b / (2 * a));

}else {

printf("x1 = %6f\n",(-1 * b + sqrt(det)) / (2 * a));

printf("x2 = %6f\n",(-1 * b - sqrt(det)) / (2 * a));

}

return 0;

}

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