Java实现-将普通表达式转换成逆波兰表达式并计算

最新推荐文章于 2025-05-06 23:14:39 发布

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最新推荐文章于 2025-05-06 23:14:39 发布 · 2.1k 阅读

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面试的时候遇到的一道题，输入逆波兰表达式，计算并输出结果。当时没写完整，事后重新写了一遍，并加了一个将普通表达式转换成逆波兰表达式的方法。

这是面试题：

/**
 * Evaluate the value of an arithmetic expression in Reverse Polish Notation.
 * 
 * Valid operators are + , - , * , / . Each operand may be an integer or another expression.
 * 
 * Some examples: 
 * ["2","1","+","3","*"] -> ( 2 + 1 ) * 3 = 9
 * ["4","13","5","/","+"] -> 4 + ( 13 / 5 ) = 6
 */
public class EvalRPN{
   
   
    public static void test() {
        Assert.assertTrue(9 == evalRPN(new String[] { "2", "1", "+", "3", "*" }));

        Assert.assertTrue(6 == evalRPN(new String[] { "4", "13", "5", "/", "+" }));
    }

    // complete this method
    public static int evalRPN(String[] tokens) {
        int returnValue = 0;