java生成四则运算表达式_生成四则运算（java实现）
|博客班級 | https://edu.cnblogs.com/campus/ahgc/AHPU-SE-19/ |
|作業(yè)要求 | https://edu.cnblogs.com/campus/ahgc/AHPU-SE-19/homework/11376|
|作業(yè)目標(biāo) | 寫一個能自動生成小學(xué)四則運(yùn)算題目的程序 |
|學(xué)號 | 3190704130 |
代碼如下：
//main函數(shù)所在區(qū)域主要實(shí)現(xiàn)生成問題
`package xiaohu;
import java.util.Scanner;
public class CT {
public static String str = "";
public static int num = 5;
public static int num_i = 0;
public static int numberRange = 100;
public static double sum = 0;
public static void main(String[] args) {
System.out.println("當(dāng)然是小胡啦");
System.out.println("控制臺實(shí)現(xiàn)出題判斷");
System.out.println("注意：結(jié)果保留1位小數(shù)！");
System.out.println("共10道題目：");
Scanner in = new Scanner(System.in);
double answer = 0;
double result = 0;
String[] question = new String[10];
int questionNumber = 0;
int answerTrue = 0;
boolean flag;
for(;😉 {
answer = 0; result = 0; flag = true; str="";
if((questionNumber + 1)%5 != 0) {
GetQuestion_int();
} else {
GetQuestion_div();
}
for(int j = questionNumber-1; j >= 0; j --) {
if(question[j].equals(str)) {
flag = false; break;
}
}
if(!flag) continue;
else {question[questionNumber] = new String(str); questionNumber++;}
System.out.print("" + questionNumber + ". " + str+" = ");
answer = in.nextDouble();
if(!str.isEmpty()) {
result = Arithmetic.arithmetic(str);
}
if(answer == result) {
System.out.println(" ??");
answerTrue++;
} else {
System.out.println(" ? " + " 正確答案：" + result);
}
if(questionNumber == 10) break; // 滿10個跳出
}
System.out.println("你的正確概率：" + answerTrue + "/10");
in.close();
}
private static void GetQuestion_int() {
//得到問題函數(shù)，在這里調(diào)用遞歸函數(shù)quesGrow()。
str = "";
sum = 0;
num_i = num;//用前都清零
quesGrow_int();
}
private static void GetQuestion_div() {
str = "";
sum = 0;
num_i = num;//用前都清零
quesGrow_div();
}
private static void quesGrow_int() {
//
if( num_i > 1 ) {
int j = num_i;//記錄這是第幾層調(diào)用。
num_i--;
quesGrow_int();//遞歸
int w=1+(int)(Math.random()*numberRange);//隨機(jī)生成一個數(shù)
int t=1+(int)(Math.random()*100);//向左生成，還是向右生成，類似于樹。
int f=1+(int)(Math.random()*100);//運(yùn)算符控制
if(t>50)//新數(shù)往右加
{
if(f>50) {
sum = sum + w;
str = str + "+" + String.valueOf( w );
}
else {
sum = sum - w;
str = str + "-" + String.valueOf( w );
}
}
else//否則 新數(shù)往左加
{
if(f>50) {
sum = w + sum;
str = String.valueOf( w ) + "+" + str;
}
else {
if( j < 3 ) {//3——摸索出的數(shù)，不用給自己套上括號。實(shí)際上就是j=2
sum = w - sum;
str = String.valueOf( w ) + "-" + str;
}
else {
sum = w - sum;
str = String.valueOf( w ) + "-" + "(" +str+ ")";
//向左添減法的時候加括號，打破順序計(jì)算模式。
}
}
}
}
else if( num_i == 1 ) {
//最后一層，也是輸出的第一層
int w=1+(int)(Math.random()*numberRange);
sum = sum + w;
str = str + String.valueOf( w );
}
}
private static void quesGrow_div() {
if( num_i > 1 ) {
int j = num_i;//記錄這是第幾層調(diào)用。
num_i--;
quesGrow_div();//遞歸
double w=Math.random();//隨機(jī)生成一個數(shù)
int t=1+(int)(Math.random()*100);//向左生成，還是向右生成，類似于樹。
int f=1+(int)(Math.random()*100);//運(yùn)算符控制
if(t>50)//新數(shù)往右加
{
if(f>50) {
sum = sum + w;
str = str + "+" + ChangeToFenshuDemo.toFenshu((""+(w+0.01)).substring(0, 4));
}
else {
sum = sum - w;
str = str + "-" + ChangeToFenshuDemo.toFenshu((""+(w+0.01)).substring(0, 4));
}
}
else//否則 新數(shù)往左加
{
if(f>50) {
sum = w + sum;
str = ChangeToFenshuDemo.toFenshu((""+(w+0.01)).substring(0, 4)) + "+" + str;
}
else {
if( j < 3 ) {//3——摸索出的數(shù)，不用給自己套上括號。實(shí)際上就是j=2
sum = w - sum;
str = ChangeToFenshuDemo.toFenshu((""+(w+0.01)).substring(0, 4)) + "-" + str;
}
else {
sum = w - sum;
str = ChangeToFenshuDemo.toFenshu((""+(w+0.01)).substring(0, 4)) + "-" + "(" +str+ ")";
//向左添減法的時候加括號，打破順序計(jì)算模式。
}
}
}
}
else if( num_i == 1 ) {
//最后一層，也是輸出的第一層
double w=Math.random();
sum = sum + w;
str = str + ChangeToFenshuDemo.toFenshu((""+(w+0.01)).substring(0, 4));
}
}
}`
//ChangeToFenshuDemo類實(shí)現(xiàn)將數(shù)轉(zhuǎn)化為分?jǐn)?shù)
`package xiaohu;
public class ChangeToFenshuDemo {
public static int getGongYueShu(int a, int b) {
int t = 0;
if(a < b){
t = a;
a = b;
b = t;
}
int c = a % b;
if(c == 0){
return b;
}else{
return getGongYueShu(b, c);
}
}
public static String toFenshu(String xiaoshu) {
String[] array = new String[2];
array = xiaoshu.split("\\.");
int a = Integer.parseInt(array[0]);//獲取整數(shù)部分
int b = Integer.parseInt(array[1]);//獲取小數(shù)部分
int length = array[1].length();
int FenZi = (int) (a * Math.pow(10, length) + b);
int FenMu = (int) Math.pow(10, length);
int MaxYueShu = getGongYueShu(FenZi, FenMu);
return new String(FenZi / MaxYueShu + "/" + FenMu / MaxYueShu);
}
}`
//Arithmetic類實(shí)現(xiàn)數(shù)的運(yùn)算
`package xiaohu;
import java.math.BigDecimal;
import java.math.MathContext;
import java.math.RoundingMode;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Arithmetic {
public static double arithmetic(String exp){
String result = parseExp(exp).replaceAll("[\[\]]", "");
return Double.parseDouble(result);
}
/**
* 解析計(jì)算四則運(yùn)算表達(dá)式，例：2+((3+4)2-22)/23
*/
public static String parseExp(String expression){
expression=expression.replaceAll("\\s+", "").replaceAll("^\\((.+)\\)$", "$1");
String minExp="^((\\d+(\\.\\d+)?)|(\\[\\-\\d+(\\.\\d+)?\\]))[\\+\\-\\*\\/]((\\d+(\\.\\d+)?)|(\\[\\-\\d+(\\.\\d+)?\\]))$";
//最小表達(dá)式計(jì)算
if(expression.matches(minExp)){
String result=calculate(expression);
return Double.parseDouble(result)>=0?result:"["+result+"]";
}
//計(jì)算不帶括號的四則運(yùn)算
String noParentheses="^[^\\(\\)]+$";
String priorOperatorExp="(((\\d+(\\.\\d+)?)|(\\[\\-\\d+(\\.\\d+)?\\]))[\\*\\/]((\\d+(\\.\\d+)?)|(\\[\\-\\d+(\\.\\d+)?\\])))";
String operatorExp="(((\\d+(\\.\\d+)?)|(\\[\\-\\d+(\\.\\d+)?\\]))[\\+\\-]((\\d+(\\.\\d+)?)|(\\[\\-\\d+(\\.\\d+)?\\])))";
if(expression.matches(noParentheses)){
Pattern patt=Pattern.compile(priorOperatorExp);
Matcher mat=patt.matcher(expression);
if(mat.find()){
String tempMinExp=mat.group();
expression=expression.replaceFirst(priorOperatorExp, parseExp(tempMinExp));
}else{
patt=Pattern.compile(operatorExp);
mat=patt.matcher(expression);
if(mat.find()){
String tempMinExp=mat.group();
expression=expression.replaceFirst(operatorExp, parseExp(tempMinExp));
}
}
return parseExp(expression);
}
//計(jì)算帶括號的四則運(yùn)算
String minParentheses="\\([^\\(\\)]+\\)";
Pattern patt=Pattern.compile(minParentheses);
Matcher mat=patt.matcher(expression);
if(mat.find()){
String tempMinExp=mat.group();
expression=expression.replaceFirst(minParentheses, parseExp(tempMinExp));
}
return parseExp(expression);
}
/**
* 計(jì)算最小單位四則運(yùn)算表達(dá)式(兩個數(shù)字)
*/
public static String calculate(String exp){
exp=exp.replaceAll("[\\[\\]]", "");
String number[]=exp.replaceFirst("(\\d)[\\+\\-\\*\\/]", "$1,").split(",");
BigDecimal number1=new BigDecimal(number[0]);
BigDecimal number2=new BigDecimal(number[1]);
BigDecimal result=null;
/*
* 設(shè)置精度，否則報錯(計(jì)算機(jī)并不知道要保留幾位，所以很干脆的報錯
*/
MathContext mc = new MathContext(2, RoundingMode.HALF_DOWN);
//精度為2，舍入模式為大于0.5進(jìn)1，否則舍棄。
String operator=exp.replaceFirst("^.*\\d([\\+\\-\\*\\/]).+$", "$1");
if("+".equals(operator)){
result=number1.add(number2);
}else if("-".equals(operator)){
result=number1.subtract(number2);
}else if("*".equals(operator)){
result=number1.multiply(number2);
}else if("/".equals(operator)){
result=number1.divide(number2,mc);
}
return result!=null?result.toString():null;
}
}`
運(yùn)行結(jié)果展示
psp表格：
總結(jié)
以上是生活随笔為你收集整理的java生成四则运算表达式_生成四则运算（java实现）的全部內(nèi)容，希望文章能夠幫你解決所遇到的問題。
- 上一篇： 初始Zookeeper
- 下一篇： robocode_Robocode大师的