题解 | 牛牛的绩点

# 定义等级到绩点的映射
grade_map = {"A": 4.0, "B": 3.0, "C": 2.0, "D": 1.0, "F": 0.0}

total_credits = 0.0  # 总学分
weighted_sum = 0.0  # 绩点×学分之和

while True:
    grade = input().strip()
    if grade == "False":  # 结束条件
        break
    credit = float(input().strip())
    total_credits += credit
    weighted_sum += grade_map[grade] * credit

# 计算均绩，保留两位小数
if total_credits > 0:
    gpa = weighted_sum / total_credits
    print("{0:.2f}".format(gpa))
else:
    print("0.00")  # 避免除以零的情况