题解 | 计算一元二次方程

#include <iostream>
using namespace std;
#include <cmath>

int main() {
    float a, b, c;
    float delta;
    float x1, x2;
    float ture, imaginary;
    while (scanf("%f %f %f", &a, &b, &c) != EOF) 
    {
        delta = b * b - 4 * a * c;
        ture = -b / (2 * a);
        imaginary = sqrt(delta) / 2 / a;
        if ( a == 0 ) {
            printf("Not quadratic equation\n");
        } else {
            if (delta == 0) {
                if (a > 0) {
                    x1 = x2 = ture + imaginary;
                    printf("x1=x2=%.2f\n", x1);
                } else {
                    x1 = x2 = ture - imaginary;
                    printf("x1=x2=%.2f\n", x1);
                }
            } else if (delta > 0) {
                x1 = ture - imaginary;
                x2 = ture + imaginary;
                printf("x1=%.2f;x2=%.2f\n", x1, x2);
            } else {
                delta = -delta;
                imaginary = sqrt(delta) / 2 / a;
                printf("x1=%.2f-%.2fi;", ture, imaginary);
                printf("x2=%.2f+%.2fi\n", ture, imaginary);
            }
        }
    }
    return 0;
}