/*** 产生运算符，个数及种类，并限制种类大于2。此处采用递归* @return int[] ope 返回生成的运算符*/private static int[] operator() {Random random = new Random();boolean flag = false;int n=random.nextInt(3)+3;  //3-5个运算符,运算符个数ope=new int[n];for (int j=0;j<n;j++)  ope[j]=random.nextInt(4);  //随机选择某个运算符for (int j = 1; j < n; j++) {               //控制运算符种类if(ope[0]!=ope[j]) flag = true;}if (!flag)  {operator();}return ope;}

   /*** 中缀表达式转化为后缀表达式* @param LinkedList<String> list* @param int n* @param String[] ss* @return int m */private static int transferToPostfix(LinkedList<String> list,int n,String[] ss){Iterator<String> it=list.iterator();while (it.hasNext()) {String s = it.next();if (isOperator(s)) {if (operators.isEmpty()) {operators.push(s);}else {//如果读入的操作符为非")"且优先级比栈顶元素的优先级高或一样，则将操作符压入栈if (priority(operators.peek())<priority(s)&&!s.equals(")")) {operators.push(s);}else if(!s.equals(")")&&priority(operators.peek())>=priority(s)){while (operators.size()!=0&&priority(operators.peek())>=priority(s)&&!operators.peek().equals("(")) {if (!operators.peek().equals("(")) {String operator=operators.pop();sb.append(operator).append(" ");                           output.push(operator);}}operators.push(s);}//如果读入的操作符是")"，则弹出从栈顶开始第一个"("及其之前的所有操作符else if (s.equals(")")) {while (!operators.peek().equals("(")) {String operator=operators.pop();sb.append(operator).append(" ");output.push(operator);}//弹出"("operators.pop();}}}//读入的为非操作符else {sb.append(s).append(" ");              output.push(s);}}if (!operators.isEmpty()) {Iterator<String> iterator=operators.iterator();while (iterator.hasNext()) {String operator=iterator.next();sb.append(operator).append(" ");output.push(operator);iterator.remove();}}int m = calculate(n,ss);sb.delete(0,sb.length());return  m ;}

          /*** 计算后缀表达式并输出到文件* @param int n* @param String[] ss* @return int n */    private static int calculate(int n,String[] ss){LinkedList<String> mList=new LinkedList<>();String[] postStr=sb.toString().split(" ");for (String s:postStr) {if (isOperator(s)){if (!mList.isEmpty()){int num1=Integer.valueOf(mList.pop());int num2=Integer.valueOf(mList.pop());if (s.equals("/")&&(num1==0||num1>num2)){n--;return n;}if(s.equals("-")&&num2%num1!=0){n--;return n;}int newNum=cal(num2,num1,s);mList.push(String.valueOf(newNum));}}else {//数字则压入栈中mList.push(s);}}String content = "";if (!mList.isEmpty()){for (int j = 0; j < ss.length; j++) {content+=ss[j];}content+="="+mList.pop()+"\r\n";}if(!file.exists()) file = new File("result.txt");         try {FileOutputStream fos = new FileOutputStream(file,true);//建立文件流,用以输出计算式           fos.write(content.getBytes());fos.flush();fos.close();} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}return n;}

public LinkedList<String> expression(){   char[] operator=new char[]{'+','-','*','/'};Random random=new Random();LinkedList<String> expression=new LinkedList<String>();int ope[]= operator(); //产生的运算符的个数int[] number=new int[ope.length+1]; //运算数的个数,该数组存储运算数for(int j=0;j<=ope.length;j++){number[j]=random.nextInt(100)+1; //4-5个数字，产生数字//此时产生的数字是[1，10]，不包括0，可以这样写，random.nextInt(20)%11//改成限制的！！！！！}int bracketnum=random.nextInt(ope.length-1); //随机产生括号的个数，题目限定括号个数小于运算符个数
//          System.out.println("括号数："+bracketnum);if (bracketnum>0) {                   //产生括号             int [] lbracketloc=new int[bracketnum];int [] rbracketloc=new int[bracketnum];int [] leftnum=new int[ope.length+1];   //记录每个数前的左括号的数量int [] rightnum=new int[ope.length+1];  //记录每个数后的右括号的数量 for (int i = 0; i <bracketnum; i++) {lbracketloc[i]=random.nextInt(ope.length); //随机产生左括号的位置,此左括号在第几个运算数前面，运算数不包括最后一个数,rbracketloc[i]=random.nextInt(ope.length)+1;//随机产生右括号的位置,此右括号在第几个运算数后面，运算数不包括第一个数if (rbracketloc[i]<=lbracketloc[i]) {      //若右括号的位置在左括号前面或左右两个括号只括住一个数字，则去掉本次产生的括号i--;                                   //这个方法只是初次保证在一次循环下产生的左右括号不括住一个数字，但仍有可能出现这种情况  }                                           //在分次循环时，仍有可能出现括住一个数字的情况}for (int i = 0; i < bracketnum; i++) {  //利用桶函数的思想，记录每个运算数对应的括号的个数leftnum[lbracketloc[i]]++;rightnum[rbracketloc[i]]++;}for (int i = 0; i < ope.length+1; i++) { // 再次进行限制，保证左右括号不是只括住一个数字。对一个数进行检查，当其左右两边的括号数相等时，if (!(leftnum[i]==0||rightnum[i]==0)) {  // 就将它两边的括号都删掉，这样只是对单个数进行了成功的限制，但若将一个表达式作为整体看待，while (!(leftnum[i]==0||rightnum[i]==0)) {      //还是会出现这种情况         leftnum[i]--;rightnum[i]--;}}}//            if (!(leftnum[0]==0||rightnum[ope.length]==0)) {        //对式子最前面和最后面的括号进行限制，不许出现括住整体式子的情况
//                  while (!(leftnum[0]==0||rightnum[ope.length]==0)) { //这样有错误
//                      leftnum[0]--;
//                      rightnum[ope.length]--;
//                  }
//              }int right=0;  //记录加进式子的右括号的数量int left=0;  // 记录加进式子的左括号的数量for (int i = 0; i < ope.length; i++) {for (int j = 0; j < leftnum[i]; j++) {expression.add("(");left++;}expression.add(String.valueOf(number[i]));for (int j = 0; j < rightnum[i]; j++) {expression.add(")");right++;}expression.add(String.valueOf(operator[ope[i]]));if(ope[i]==3){number[i+1]=decide(number[i],number[i+1]); //此处为整除的初步控制，控制可能会无效，因为在某些情况下//加上括号后，整体的运算整个都变了，要在计算过程中去二次控制整除}                                             //在下面不加括号的处理中，也会因为运算顺序的改变而出现控制无效的情况}                                                 //所以这段代码只能初步控制整除expression.add(String.valueOf(number[ope.length]));for (int i = right; i < left; i++) {expression.add(")");}        }else {for(int i=0;i<ope.length;i++){expression.add(String.valueOf(number[i]));expression.add(String.valueOf(operator[ope[i]]));if(ope[i]==3){number[i+1]=decide(number[i],number[i+1]);}}expression.add(String.valueOf(number[ope.length]));        }
//          System.out.println(expression);    return expression;}

 public void Generate(int num){ //执行整数计算Random random = new Random();CalCu cu = new CalCu();int n=0;while (n<num) {int choose = random.nextInt(3);// System.out.println("suijishu:"+choose);if(choose==0||choose==1){LinkedList<String> list=new LinkedList<>();list=new CalCu().expression();Iterator<String> it=list.iterator();StringBuilder sd=new StringBuilder();while (it.hasNext()) {               sd.append(it.next()).append(" ");}String[] ss=sd.toString().split(" ");n = cu.transferToPostfix(list,n,ss);n++;}else {cu.MakeFraction();n++;}}}