题解 | #游游开车出游#（Python）

# 给出 v，x，y，求 y/(v+x*t)+t 最小
# 凹函数，先下降再上升，三分法求解
v, x, y = map(float, input().split())

def cal(t):
    return y/(v+x*t)+t

left = 0
right = 2e9
# 题目要求精确率1e-6
while(right-left>1e-7):
    fm = (right-left) / 3.0
    fl = left + fm
    fr = fl + fm
    if (cal(fl)<cal(fr)):
        right = fr
    else:
        left = fl
print('%0.9f'%cal(left))