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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6. import java.util.Scanner;
  7. import java.util.StringTokenizer;
  8. class steck {
  9.     private int size;
  10.     private Object[] date;
  11.     private int capacity;
  12.     public steck(){
  13.         date = new Object[2];
  14.         capacity = 2;
  15.     }
  16.     public steck(int x){
  17.         date = new Object[x];;
  18.         capacity = x;
  19.     }
  20.  
  21.     public boolean isEmpty(){
  22.         return size == 0;
  23.     }
  24.  
  25.     private void resize(int x){
  26.         Object[] newDate = new Object[x];
  27.         System.arraycopy(date, 0, newDate, 0, size);
  28.         date = null;
  29.         date = newDate;
  30.     }
  31.  
  32.     public void push(Object x){
  33.         if(size == capacity){
  34.             resize(2*capacity);
  35.         }
  36.         date[size++] = x;
  37.     }
  38.  
  39.     public Object pop(){
  40.         if(isEmpty()){
  41.             return null;
  42.         }
  43.         if(size < capacity/2){
  44.             resize(capacity/2);
  45.         }
  46.         Object temp = date[size -1];
  47.         size = size -1;
  48.         return temp;
  49.     }
  50.  
  51.     public Object peek(){
  52.         if(isEmpty()) return null;
  53.         return date[size-1];
  54.     }
  55.  
  56.     public void clear(){
  57.         size = 0;
  58.     }
  59.  
  60.     public int size(){
  61.         return size;
  62.     }
  63.     public int getCapacity(){
  64.         return size;
  65.     }
  66. }
  67. /**
  68.  * Created by green on 20.12.15.
  69.  */
  70. class Parser{
  71.         private String operators = "u+-*/";
  72.         private String delimiters = operators + "( )";
  73.         public boolean correct = true;
  74.         private boolean isOperator(String x){
  75.             if(x.length() != 1) return false;
  76.             for(int i = 0; i < operators.length(); i++){
  77.                 if(x.charAt(0) == operators.charAt(i)) return true;
  78.             }
  79.             return false;
  80.         }
  81.         private boolean isDelimiter(String x){
  82.             if(x.length() != 1) return false;
  83.             for(int i = 0; i < delimiters.length(); i++){
  84.                 if(x.charAt(0) == delimiters.charAt(i)) return true;
  85.             }
  86.             return false;
  87.         }
  88.         private int priority(String x) {
  89.             if (x.equals("(")) return 1;
  90.             if (x.equals("+") || x.equals("-")) return 2;
  91.             if (x.equals("*") || x.equals("/")) return 3;
  92.             return 4;
  93.         }
  94.         public String parse(String infix) {
  95.             String postfix = "";
  96.             steck stack = new steck();
  97.             StringTokenizer tokenizer = new StringTokenizer(infix, delimiters, true);
  98.             String prev = "", curr = "";
  99.             while (tokenizer.hasMoreTokens()) {
  100.                 curr = tokenizer.nextToken();
  101.                 if (!tokenizer.hasMoreTokens() && isOperator(curr)) {
  102.                     postfix = ("Некорректное выражение.");
  103.                     correct = false;
  104.                     return postfix;
  105.                 }
  106.                 if (curr.equals(" ")) continue;
  107.                 if (isDelimiter(curr)) {
  108.                     if (curr.equals("(")) stack.push(curr);
  109.                     else if (curr.equals(")")) {
  110.                         while (!stack.peek().equals("(")) {
  111.                             postfix += stack.pop().toString() + " ";
  112.                             if (stack.isEmpty()) {
  113.                                 postfix = ("Скобки не согласованы.");
  114.                                 correct = false;
  115.                                 return postfix;
  116.                             }
  117.                         }
  118.                         stack.pop();
  119.                     }else {
  120.                         if (curr.equals("-") && (prev.equals("") || (isDelimiter(prev)  && !prev.equals(")")))) {
  121.                             curr = "u";
  122.                         }else{
  123.                             while (!stack.isEmpty() && (priority(curr) <= priority(stack.peek().toString()))) {
  124.                                 postfix += stack.pop().toString()  + " ";
  125.                             }
  126.  
  127.                         }
  128.                         stack.push(curr);
  129.                     }
  130.  
  131.                 }else {
  132.                     postfix += curr + " ";
  133.                 }
  134.                 prev = curr;
  135.             }
  136.             while (!stack.isEmpty()) {
  137.                 if (isOperator(stack.peek().toString())) postfix += stack.pop().toString() + " ";
  138.                 else {
  139.                     postfix = "Скобки не согласованы.";
  140.                     correct = false;
  141.                     return postfix;
  142.                 }
  143.             }
  144.             return postfix;
  145.         }
  146.     public int calc(String postfix) {
  147.         if(!correct) return 0;
  148.         steck stack = new steck();
  149.         for (int i = 0; i < postfix.length() ; i++) {
  150.             if(postfix.charAt(i) == ' ') continue;
  151.             if (postfix.charAt(i) == '+') stack.push(Integer.valueOf(stack.pop().toString()) + Integer.valueOf(stack.pop().toString()));
  152.             else if (postfix.charAt(i) == '-') {
  153.                 int b = Integer.valueOf(stack.pop().toString()), a = Integer.valueOf(stack.pop().toString());
  154.                 stack.push(a - b);
  155.             }
  156.             else if (postfix.charAt(i) == '*') stack.push(Integer.valueOf(stack.pop().toString()) * Integer.valueOf(stack.pop().toString()));
  157.             else if (postfix.charAt(i) == '/') {
  158.                 int b = Integer.valueOf(stack.pop().toString()), a = Integer.valueOf(stack.pop().toString());
  159.                 stack.push(a / b);
  160.             }
  161.             else if (postfix.charAt(i) == 'u') stack.push(-Integer.valueOf(stack.pop().toString()));
  162.             else{
  163.                 int g = postfix.indexOf(' ',i);
  164.                 stack.push(Integer.valueOf(postfix.substring(i, g)));
  165.                 i = g;
  166.             }
  167.         }
  168.         return Integer.valueOf(stack.pop().toString());
  169.     }
  170. }
  171.  
  172. class Ideone
  173. {
  174. 	public static void main (String[] args) throws java.lang.Exception
  175. 	{
  176. 		Scanner in = new Scanner(System.in);
  177.         String s = "15 * -(3 - 4)";
  178.         Parser x = new Parser();
  179.         s = x.parse(s);
  180.         if(x.correct){
  181.             System.out.println(s);
  182.             System.out.println(x.calc(s));
  183.         }else{
  184.             System.out.println("Ошибка:"+s);
  185.         }
  186. 	}
  187. }
Success #stdin #stdout 0.17s 321344KB
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Standard input is empty
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15 3 4 - u * 
15
https://ideone.com/RflPPM
language:
Java (12.0.1)
created:
9 years ago
visibility:
secret

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