检查三个布尔值中的至少两个是否为真

2022-01-19 00:00:00 boolean boolean-logic java

一位面试官最近问我这个问题:给定三个布尔变量 a、b 和 c，如果三个中至少有两个为真，则返回真.

An interviewer recently asked me this question: given three boolean variables, a, b, and c, return true if at least two out of the three are true.

我的解决方案如下:

boolean atLeastTwo(boolean a, boolean b, boolean c) {
    if ((a && b) || (b && c) || (a && c)) {
        return true;
    }
    else{
        return false;
    }
}

他说这可以进一步改进，但是如何呢?

He said that this can be improved further, but how?

推荐答案

而不是写:

if (someExpression) {
    return true;
} else {
    return false;
}

写:

return someExpression;

<小时>

至于表达式本身，是这样的:

As for the expression itself, something like this:

boolean atLeastTwo(boolean a, boolean b, boolean c) {
    return a ? (b || c) : (b && c);
}

或者这个(你觉得更容易掌握的那个):

or this (whichever you find easier to grasp):

boolean atLeastTwo(boolean a, boolean b, boolean c) {
    return a && (b || c) || (b && c);
}

a 和 b 只测试一次，c 最多测试一次.

It tests a and b exactly once, and c at most once.

  • JLS 15.25 条件运算符?:

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