课程及格所需分数计算器数学逻辑Bug排查求助

问题根源 #

你的计算公式完全不符合加权成绩的计算逻辑，导致输出结果严重偏离预期。正确的加权成绩计算逻辑是：

总评成绩 = 当前成绩 × (1 - 期末权重占比) + 期末成绩 × 期末权重占比

从这个公式反推期末所需成绩，整理后得到正确的计算公式：
期末成绩 = (目标总评 × 100 - 当前成绩 × (100 - 期末权重)) / 期末权重

修正后的代码 #

替换错误的计算逻辑，同时新增非数字输入的异常处理，避免程序崩溃：

var goal by remember { mutableStateOf("") }
var currentGrade by remember { mutableStateOf("") }
var finalWeight by remember { mutableStateOf("") }
var finalGradeNeeded by remember { mutableStateOf("") }

if (goal.isNotEmpty() && currentGrade.isNotEmpty() && finalWeight.isNotEmpty()) {
    val goalDouble = goal.toDoubleOrNull()
    val currentDouble = currentGrade.toDoubleOrNull()
    val weightDouble = finalWeight.toDoubleOrNull()

    when {
        weightDouble == null || weightDouble == 0.0 -> {
            finalGradeNeeded = "Error: Invalid weight"
        }
        goalDouble == null || currentDouble == null -> {
            finalGradeNeeded = "Error: Invalid number input"
        }
        else -> {
            val required = (goalDouble * 100 - currentDouble * (100 - weightDouble)) / weightDouble
            finalGradeNeeded = String.format("%.1f", required)
        }
    }
}

Text(
    text = "Your final grade needs to be: $finalGradeNeeded%",
    fontWeight = FontWeight.Bold,
    fontSize = 15.sp
)

验证示例 #

输入当前成绩50、目标成绩50、期末权重50时，代入公式计算：
(50×100 - 50×(100-50)) /50 = (5000 -2500)/50 = 2500/50 =50，输出结果为50.0%，符合预期。

内容的提问来源于stack exchange，提问作者notryan