Java 算24点

import java.util.Scanner;

//测试过了，大概的都能算出来，不过bug还是有点多，发现的评论区说一下我再改改

public class The_24 {

public static void main(String[] args) {

int[] a = new int[4];// 四个数字

for (int i = 0; i < 4; i++) {

a[i] = shuZhi();

}

shuZi(a);

}

// 输入数值

public static int shuZhi() {//实现判断输入数值是否符合24点游戏规则

Scanner s = new Scanner(System.in);

int a = s.nextInt();

while (a < 1 || a > 13) {

System.out.println("输入的数值不对，请重新输入");

a = s.nextInt();

}

return a;

}

// 数字的组合

public static void shuZi(int[] a) {//a.b,c,d的排列组合

char[] f = { '+', '-', '*', '/' };// 运算符

int flag = 0;

for (int i = 0; i < 4; i++) {

for (int j = 0; j < 4; j++) {

for (int k = 0; k < 4; k++) {

for (int l = 0; l < 4; l++) {

if (i != j && i != k && i != l && j != k && j != l && k != l) {// a,b,c,d不重复

if (zuHe(f, a[i], a[j], a[k], a[l]) == 1) {

flag = 1;

}

}

}

}

}

}

if (flag == 0) {

System.out.println("无解");

}

}

// 式子的组合

public static int zuHe(char[] f, int a1, int a2, int a3, int a4) {

String s = "" + a1;

int flag = 0;

for (int i = 0; i < 4; i++) {// 运算符的与数字的排列组合（这里可能不全面，有更好方法的评论区说一下，谢谢）

String s1 = s + f[i] + a2;

for (int j = 0; j < 4; j++) {

String s2 = s1 + f[j] + a3;

for (int k = 0; k < 4; k++) {

String s3 = s2 + f[k] + a4;

if (biaoDaShi(s3) == 1) {

flag = 1;

}

s3 = s2;

}

}

}

return flag;

}

// 运算符的优先级

public static int yunSuan(char c) {

if (c == '+' || c == '-') {

return 1;

} else if (c == '*' || c == '/') {

return 2;

} else

return 0;

}

// 表达式求值

public static int biaoDaShi(String s1) {

String s = s1 + "#";

String n = "";

double[] zhan1 = new double[100];// 数值栈

char[] zhan2 = new char[100];// 运算符栈

zhan2[0] = '#';

char a;// 当前元素

int flag = 0, x = 1, top1 = -1, top2 = 0;// 栈指针

for (int i = 0; i < s.length(); i++)// 转换为后缀表达式

{

a = s.charAt(i);

if (a <= 57 && a >= 48)// 判断是否为数字

{

n = n + a;

x++;

} else

x = 0;

if (x == 0 && n != "") {

top1++;

zhan1[top1] = Integer.valueOf(n);

n = "";

}

if (a == '+' || a == '-' || a == '*' || a == '/' || a == '(' || a == ')' || a == '#') {

for (int j = 0; j <= top2; j++) {

if (yunSuan(a) <= yunSuan(zhan2[top2]) && a != '(') {

switch (zhan2[top2]) {

case '+':

zhan1[top1 - 1] = zhan1[top1 - 1] + zhan1[top1];

top1--;

top2--;

break;

case '-':

zhan1[top1 - 1] = zhan1[top1 - 1] - zhan1[top1];

top1--;

top2--;

break;

case '*':

zhan1[top1 - 1] = zhan1[top1 - 1] * zhan1[top1];

top1--;

top2--;

break;

case '/':

zhan1[top1 - 1] = zhan1[top1 - 1] / zhan1[top1];

top1--;

top2--;

break;

case '(':

top2--;

break;

case '#':

top2--;

break;

default:

top2--;

break;

}

}

}

if (yunSuan(a) > yunSuan(zhan2[top2]) || a == '(') {

top2++;

zhan2[top2] = a;

}

}

}

if (top1 == 0 && top2 == 0) {// 运算结束

if (zhan1[0] == 24) {//结果等于24就输出

System.out.println(s1 + "=" + zhan1[0]);

flag = 1;

}

} else

System.out.print("no");

return flag;

}

}

//<Date 2018-6.16>