题解 | #BC73 计算一元二次方程#

#include <stdio.h>
#include <math.h>

int main() {
    float a, b, c, d;
    while (scanf("%f %f %f", &a, &b, &c) != EOF) {
        if (a == 0.0) {
            printf("Not quadratic equation\n");
        } else {
            float x1, x2;
            d = b * b - 4 * a * c;
            if (d == 0.0) {
                x1 = x2 = -b / (2 * a);
                if (b == 0.0) {
                    x1 = x2 = 0.0;
                }
                printf("x1=x2=%.2f\n", x1, x2);
            } else if (d > 0) {
                x1 = (-b - sqrt(d))/(2 * a);
                x2 = (-b + sqrt(d))/(2 * a);
                printf("x1=%.2f;x2=%.2f\n", x1, x2);
            } else {
                float imag = sqrt(-d)/(2 * a);
                if (imag < 0) {
                    imag = -imag;
                }
                printf("x1=%.2f-%.2fi;x2=%.2f+%.2fi\n", -b/(2*a), imag, -b/(2*a), imag);
            }
        }
    }
    return 0;
}