Java 算24點

import java.util.Scanner;

//測試過了，大概的都能算出來，不過bug還是有點多，發現的評論區說一下我再改改

public class The_24 {

public static void main(String[] args) {

int[] a = new int[4];// 四個數字

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

a[i] = shuZhi();

}

shuZi(a);

}

// 輸入數值

public static int shuZhi() {//實作判斷輸入數值是否符合24點遊戲規則

Scanner s = new Scanner(System.in);

int a = s.nextInt();

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

System.out.println("輸入的數值不對，請重新輸入");

a = s.nextInt();

}

return a;

}

// 數字的組合

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

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

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不重複

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

flag = 1;

}

}

}

}

}

}

if (flag == 0) {

System.out.println("無解");

}

}

// 式子的組合

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++) {// 運算符的與數字的排列組合（這裡可能不全面，有更好方法的評論區說一下，謝謝）

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;

}

// 運算符的優先級

public static int yunSuan(char c) {

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

return 1;

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

return 2;

} else

return 0;

}

// 表達式求值

public static int biaoDaShi(String s1) {

String s = s1 + "#";

String n = "";

double[] zhan1 = new double[100];// 數值棧

char[] zhan2 = new char[100];// 運算符棧

zhan2[0] = '#';

char a;// 目前元素

int flag = 0, x = 1, top1 = -1, top2 = 0;// 棧指針

for (int i = 0; i < s.length(); i++)// 轉換為字尾表達式

{

a = s.charAt(i);

if (a <= 57 && a >= 48)// 判斷是否為數字

{

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) {// 運算結束

if (zhan1[0] == 24) {//結果等于24就輸出

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

flag = 1;

}

} else

System.out.print("no");

return flag;

}

}

//<Date 2018-6.16>