利用Java编写24点小游戏的实例代码

话不多说直接给大家上代码

package com.company;import java.util.*;/** * 24点小游戏 * 游戏规则：系统自动生成4个1-10的随机整数，玩家通过加减乘除操作，得到结果为24，每个数字只能使用一次 */public class Game24Player { final String[] patterns = {'nnonnoo', 'nnonono', 'nnnoono', 'nnnonoo', 'nnnnooo'}; final String ops = '+-*/^';//存储运算符 String solution;//解题答案 List<Integer> digits; public static void main(String[] args) { new Game24Player().play(); } void play() { digits = getSolvableDigits(); Scanner in = new Scanner(System.in); while (true) { System.out.println('24点小游戏：'); System.out.print('使用以下数字得出24点: '); System.out.println(digits); System.out.println('tips:输入q退出游戏，输入s打印解法以及出下一道题'); System.out.print('> '); String line = in.nextLine();//获取控制台下一行输入的内容 if (line.equalsIgnoreCase('q')) { System.out.println('nThanks for playing'); return; } if (line.equalsIgnoreCase('s')) { System.out.println(solution); digits = getSolvableDigits(); continue; } char[] entry = line.replaceAll('[^*+-/)(d]', '').toCharArray(); try { validate(entry); if (evaluate(infixToPostfix(entry))) { System.out.println('n恭喜你，回答正确，请继续下一轮 '); digits = getSolvableDigits(); } else { System.out.println('n答题错误，请重新答题'); } } catch (Exception e) { System.out.printf('%n%s 请重新输入.%n', e.getMessage()); } } } //判断玩家在控制台输入的内容是否正确 void validate(char[] input) throws Exception { int total1 = 0, parens = 0, opsCount = 0; for (char c : input) { if (Character.isDigit(c)) total1 += 1 << (c - ’0’) * 4; else if (c == ’(’) parens++; else if (c == ’)’) parens--; else if (ops.indexOf(c) != -1) opsCount++; if (parens < 0) throw new Exception('括号不匹配.'); } if (parens != 0) throw new Exception('括号不匹配.'); if (opsCount != 3) throw new Exception('错误输入.'); int total2 = 0; for (int d : digits) total2 += 1 << d * 4; if (total1 != total2) throw new Exception('输入有误.'); } boolean evaluate(char[] line) throws Exception { Stack<Float> s = new Stack<>(); try { for (char c : line) { if (’0’ <= c && c <= ’9’) s.push((float) c - ’0’); else s.push(applyOperator(s.pop(), s.pop(), c)); } } catch (EmptyStackException e) { throw new Exception('输入无效，请重新输入.'); } return (Math.abs(24 - s.peek()) < 0.001F); } float applyOperator(float a, float b, char c) { switch (c) { case ’+’: return a + b; case ’-’: return b - a; case ’*’: return a * b; case ’/’: return b / a; default: return Float.NaN; } } //获取一组随机数 List<Integer> randomDigits() { Random r = new Random(); List<Integer> result = new ArrayList<>(4); for (int i = 0; i < 4; i++) result.add(r.nextInt(9) + 1);//添加4个1-10的随机数 return result; } List<Integer> getSolvableDigits() { List<Integer> result; do { result = randomDigits(); } while (!isSolvable(result)); return result; } boolean isSolvable(List<Integer> digits) { Set<List<Integer>> dPerms = new HashSet<>(4 * 3 * 2); permute(digits, dPerms, 0); int total = 4 * 4 * 4; List<List<Integer>> oPerms = new ArrayList<>(total); permuteOperators(oPerms, 4, total); StringBuilder sb = new StringBuilder(4 + 3); for (String pattern : patterns) { char[] patternChars = pattern.toCharArray(); for (List<Integer> dig : dPerms) { for (List<Integer> opr : oPerms) { int i = 0, j = 0; for (char c : patternChars) { if (c == ’n’) sb.append(dig.get(i++)); else sb.append(ops.charAt(opr.get(j++))); } String candidate = sb.toString(); try { if (evaluate(candidate.toCharArray())) { solution = postfixToInfix(candidate); return true; } } catch (Exception ignored) { } sb.setLength(0); } } } return false; } String postfixToInfix(String postfix) { class Expression { String op, ex; int prec = 3; Expression(String e) { ex = e; } Expression(String e1, String e2, String o) { ex = String.format('%s %s %s', e1, o, e2); op = o; prec = ops.indexOf(o) / 2; } } Stack<Expression> expr = new Stack<>(); for (char c : postfix.toCharArray()) { int idx = ops.indexOf(c); if (idx != -1) { Expression r = expr.pop(); Expression l = expr.pop(); int opPrec = idx / 2; if (l.prec < opPrec) l.ex = ’(’ + l.ex + ’)’; if (r.prec <= opPrec) r.ex = ’(’ + r.ex + ’)’; expr.push(new Expression(l.ex, r.ex, '' + c)); } else { expr.push(new Expression('' + c)); } } return expr.peek().ex; } char[] infixToPostfix(char[] infix) throws Exception { StringBuilder sb = new StringBuilder(); Stack<Integer> s = new Stack<>(); try { for (char c : infix) { int idx = ops.indexOf(c); if (idx != -1) { if (s.isEmpty()) s.push(idx); else { while (!s.isEmpty()) { int prec2 = s.peek() / 2; int prec1 = idx / 2; if (prec2 >= prec1)sb.append(ops.charAt(s.pop())); elsebreak; } s.push(idx); } } else if (c == ’(’) { s.push(-2); } else if (c == ’)’) { while (s.peek() != -2) sb.append(ops.charAt(s.pop())); s.pop(); } else { sb.append(c); } } while (!s.isEmpty()) sb.append(ops.charAt(s.pop())); } catch (EmptyStackException e) { throw new Exception('Invalid entry.'); } return sb.toString().toCharArray(); } void permute(List<Integer> lst, Set<List<Integer>> res, int k) { for (int i = k; i < lst.size(); i++) { Collections.swap(lst, i, k); permute(lst, res, k + 1); Collections.swap(lst, k, i); } if (k == lst.size()) res.add(new ArrayList<>(lst)); } void permuteOperators(List<List<Integer>> res, int n, int total) { for (int i = 0, npow = n * n; i < total; i++) res.add(Arrays.asList((i / npow), (i % npow) / n, i % n)); }}

运行结果截图

游戏题目

在控制台输入答案

输入s是查看结果并开始下一次游戏。

输入q是退出游戏。

总结

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