update,

2025-01-31 19:15:17 +08:00
parent 09adae8c8e
commit 6c60a73f30
1546 changed files with 286918 additions and 0 deletions
--- a/_resources/it114105/itp4510/Lab03/Lab3.2/EvaPostfix.java
+++ b/_resources/it114105/itp4510/Lab03/Lab3.2/EvaPostfix.java
@@ -0,0 +1,101 @@
+import java.util.Scanner;
+
+public class EvaPostfix {
+    public static void main(String[] args) {
+        Stack s = new LinkedStack();
+        Scanner keyboard = new Scanner(System.in);
+        System.out.print("Input the infix expression? ");
+        String exp = keyboard.nextLine();
+        try {
+            if (parenthesisMatching(exp)) {
+                for (int i = 0; i < exp.length(); i++) {
+                    char item = exp.charAt(i);
+                    if (item == '(' || item == '{' || item == '[') {
+                        s.push(item);
+                    } else if (isOperater(item)) {
+                        if (s.isEmpty()) {
+                            s.push(item);
+                        } else if ((checkVal(item) == checkVal((char) s.top())) || (checkVal(item) < checkVal((char) s.top()))) {
+                            System.out.print(s.pop());
+                            if(s.isEmpty()){
+                                s.push(item);
+                                }else if(checkVal((char) s.top()) == checkVal(item)) {
+                                while (checkVal(item) == checkVal((char) s.top())) {
+                                    System.out.print(s.pop());
+                                    if (s.isEmpty()) {
+                                        s.push(item);
+                                        break;
+                                    }
+                                }
+                            } else {
+                                s.push(item);
+                            }
+                        } else if (checkVal(item) > checkVal((char) s.top())) {
+                            s.push(item);
+                        }
+                    } else if (item == ')' || item == ']' || item == '}') {
+                        while (((char) s.top() != '(')&&((char) s.top() != '{') && ((char) s.top() != '[')) {
+                            System.out.print(s.pop());
+                        }
+                        s.pop();
+                    } else {
+                        System.out.print(item);
+                    }
+                }
+                while (!s.isEmpty()) {
+                    System.out.print(s.pop());
+                }
+            } else {
+                System.out.println("Error");
+            }
+        } catch (StackEmptyException e) {
+            System.out.println("Parenthesis not matched");
+        } catch (StackFullException e) {
+            System.out.println("Parenthesis not matched");
+        }
+    }
+
+    public static boolean parenthesisMatching(String exp) throws StackFullException, StackEmptyException {
+        Stack s = new LinkedStack();
+        char item;
+        for (int i = 0; i < exp.length(); i++) {
+            item = exp.charAt(i);
+            if (item == '{' || item == '(' || item == '[') {
+                s.push(item);
+            } else if (item == '}' || item == ')' || item == ']') {
+                char x = (char) s.pop();
+                if ((x != '(') && (x != '[') && (x != '{')) {
+                    return false;
+                }
+            }
+        }
+        if (s.isEmpty()) {
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    public static boolean isOperater(char exp) {
+        switch (exp) {
+            case '+':
+            case '-':
+            case '*':
+            case '/':
+                return true;
+            default:
+                return false;
+        }
+    }
+
+    public static int checkVal(char exp) {
+        if (exp == '*' || exp == '/') {
+            return 5;
+        } else if (exp == '+' || exp == '-') {
+            return 3;
+        } else {//'('
+            return -1;
+        }
+
+    }
+}