first commit add out file

Project/Project.iml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

Project/src/Main.java

@@ -0,0 +1,93 @@
+import java.util.Stack;
+
+public class Main {
+
+    private static String[] op = { "+", "-", "*", "/" };// Operation set
+    public static void main(String[] args) {
+        String question = MakeFormula();
+        System.out.println(question);
+        String ret = Solve(question);
+        System.out.println(ret);
+    }
+
+    public static String MakeFormula(){
+        StringBuilder build = new StringBuilder();
+        int count = (int) (Math.random() * 2) + 1; // generate random count
+        int start = 0;
+        int number1 = (int) (Math.random() * 99) + 1;
+        build.append(number1);
+        while (start <= count){
+            int operation = (int) (Math.random() * 3); // generate operator
+            int number2 = (int) (Math.random() * 99) + 1;
+            build.append(op[operation]).append(number2);
+            start ++;
+        }
+        return build.toString();
+    }
+
+    public static String Solve(String formula){
+        Stack<String> tempStack = new Stack<>();//Store number or operator
+        Stack<Character> operatorStack = new Stack<>();//Store operator
+        int len = formula.length();
+        int k = 0;
+        for(int j = -1; j < len - 1; j++){
+            char formulaChar = formula.charAt(j + 1);
+            if(j == len - 2 || formulaChar == '+' || formulaChar == '-' || formulaChar == '/' || formulaChar == '*') {
+                if (j == len - 2) {
+                    tempStack.push(formula.substring(k));
+                }
+                else {
+                    if(k < j){
+                        tempStack.push(formula.substring(k, j + 1));
+                    }
+                    if(operatorStack.empty()){
+                        operatorStack.push(formulaChar); //if operatorStack is empty, store it
+                    }else{
+                        char stackChar = operatorStack.peek();
+                        if ((stackChar == '+' || stackChar == '-')
+                                && (formulaChar == '*' || formulaChar == '/')){
+                            operatorStack.push(formulaChar);
+                        }else {
+                            tempStack.push(operatorStack.pop().toString());
+                            operatorStack.push(formulaChar);
+                        }
+                    }
+                }
+                k = j + 2;
+            }
+        }
+        while (!operatorStack.empty()){ // Append remaining operators
+            tempStack.push(operatorStack.pop().toString());
+        }
+        Stack<String> calcStack = new Stack<>();
+        for(String peekChar : tempStack){ // Reverse traversing of stack
+            if(!peekChar.equals("+") && !peekChar.equals("-") && !peekChar.equals("/") && !peekChar.equals("*")) {
+                calcStack.push(peekChar); // Push number to stack
+            }else{
+                int a1 = 0;
+                int b1 = 0;
+                if(!calcStack.empty()){
+                    b1 = Integer.parseInt(calcStack.pop());
+                }
+                if(!calcStack.empty()){
+                    a1 = Integer.parseInt(calcStack.pop());
+                }
+                switch (peekChar) {
+                    case "+":
+                        calcStack.push(String.valueOf(a1 + b1));
+                        break;
+                    case "-":
+                        calcStack.push(String.valueOf(a1 - b1));
+                        break;
+                    case "*":
+                        calcStack.push(String.valueOf(a1 * b1));
+                        break;
+                    default:
+                        calcStack.push(String.valueOf(a1 / b1));
+                        break;
+                }
+            }
+        }
+        return formula + "=" + calcStack.pop();
+    }
+}