Question

我已经为这个问题工作了几天而且我最后都在工作。代码适用于0到9之间的输入数字。但是当输入大于9时，例如28 72 * 13 + 20 67 * +，它不会打印正确的答案。我不知道要编写代码来实现什么。我不能改变主要功能。我只能在static int evaluatePostfix（char [] izraz，int n）

内部进行更改

注意：我修好了。

    import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.NoSuchElementException;

interface Stack<E> {

    // The elements of the Stack are any kind of objects

    // Access methods:

    public boolean isEmpty ();
        // Returns true only if the stack is empty.

 public E peek ();

    public void clear ();
        // Clears the stack.

    public void push (E x);
        // Adds x on the top of the stack.

    public E pop ();
        // Removes and returns the element on the top.


}

class ArrayStack<E> implements Stack<E> {
    private E[] elems;
    private int depth;

    @SuppressWarnings("unchecked")
    public ArrayStack (int maxDepth) {
        // Creating new empty stack
        elems = (E[]) new Object[maxDepth];
        depth = 0;
    }


    public boolean isEmpty () {
         // Returns true only if the stack is empty.

        return (depth == 0);
    }

  public E peek () {
        // Returns the element on the top od the stack.
        if (depth == 0)
            throw new NoSuchElementException();
        return elems[depth-1];
    }


    public void clear () {
        // Clears the stack.
        for (int i = 0; i < depth; i++)  elems[i] = null;
        depth = 0;
    }


    public void push (E x) {
        // Adds x on the top of the stack.
        elems[depth++] = x;
    }


    public E pop () 
    {
        // Removes and returns the element on the top.
        if (depth == 0)
            throw new NoSuchElementException();
        E topmost = elems[--depth];
        elems[depth] = null;
        return topmost;
    }


}


public class PostFixEvaluation 
{    
    static int evaluate(int op1, int op2, char ch)
    {
        switch (ch) {
      case '*': return op2 * op1;
      case '/': return op2 / op1;
      case '+': return op2 + op1;
      case '-': return op2 - op1;
      default : return 0;
   }
}


    static int evaluatePostfix(char [] izraz, int n)
{
        ArrayStack<String> e = new ArrayStack<String>(n);
        char ch=0;
        int op1,op2,result=0;
        int i=0;
      while(i<n)
    {
            if(izraz[i]=='+' || izraz[i]=='-' || izraz[i]=='/' || izraz[i]=='*')
           {
                ch=izraz[i];
                op1 =Integer.parseInt(e.pop());
                op2 =Integer.parseInt(e.pop());
                result=evaluate(op1,op2,ch);    
                e.push(Integer.toString(result));                 
           }

          else
       {
         final StringBuilder number= new StringBuilder();
if(Character.isDigit(izraz[i]))
            {
         while (izraz[i] != ' ') 
          {
           number.append(izraz[i]);
           i++;    
          }

         e.push(number.toString());
         continue;
            }
       } 
            i++;                          
    }


        return result;
}

    public static void main(String[] args) throws Exception{

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String expression = br.readLine();
        char exp[] = expression.toCharArray();

        int rez = evaluatePostfix(exp, exp.length);
       System.out.println(rez);

        br.close();

    }

}

Answer 1

而不是Character，请尝试使用以下字符串：

替换此代码：

    ArrayStack<Character> e = new ArrayStack(n);
    char ch=0,res=0,a,b;
    int op1,op2,result=0,c=0;
    int z;
    for(int i=0; i<n; i++)
    {
       if(Character.isDigit(izraz[i]))
       {

          ch=izraz[i];

          e.push(ch);  


       }
        if(izraz[i]=='+' || izraz[i]=='-' || izraz[i]=='/' || izraz[i]=='*')
       {
           ch=izraz[i];

           op1 =e.pop()-'0';
            //System.out.print(op1+" ");

           op2 =e.pop()-'0';

使用：

    ArrayStack<String> e = new ArrayStack<String>(n);
    char ch=0;
    int op1,op2,result=0;
    for(int i=0; i<n; i++)
    {
       if(Character.isDigit(izraz[i]))
       {
         final StringBuilder number= new StringBuilder();

         while (izraz[i] != ' ') {
           number.append(izraz[i]);
           i++;    
         }

         e.push(number.toString());

          continue;
       }
        if(izraz[i]=='+' || izraz[i]=='-' || izraz[i]=='/' || izraz[i]=='*')
       {
           ch=izraz[i];

           op1 =Integer.parseInt(e.pop());
            //System.out.print(op1+" ");

           op2 =Integer.parseInt(e.pop());

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1 个答案: