【程序5】填运算符

ゝ一纸荒年。 2022-08-09 13:59 7阅读 0赞

**\[java\]**  [view plain][] [copy][view plain]

1.  /\*【程序5】 
2.   \* 在下面的算式中添加上“+、-、\*、/”运算符，使等式成立（不使用括号）； 
3.   \* 5   5   5   5   5 = 5 
4.   \* 1.4  枚举(穷举)算法 
5.   \* 1.4.3  实例：填运算符 
6.   \*  
7.      由于算术表达式的特殊性，在编程求解这个算式时，需要注意以下几点： 
8.      当填入除号时，要求右侧的数不能为0。 
9.      乘除的运算级别比加减高。             
10.  
11.     5 + 5 - 5 \* 5 / 5 = 5 
12.  \*/  
13.   
14. **import** java.util.Scanner;  
15. **public** **class** T005 \{  
16.     **public** **static** **void** main(String\[\] args)\{  
17.         Scanner scan = **new** Scanner(System.in);  
18.         System.out.print("输入5个数：");  
19.         **int** num\[\] = **new** **int**\[5\];  
20.         **for**(**int** i=0;i<5;i++)\{  
21.             num\[i\] = scan.nextInt();  
22.         \}  
23.         System.out.print("输入结果：");  
24.         **int** result = scan.nextInt();      
25.         **char**\[\] oper = \{ '+','-','\*','/'\};  
26.         **int** count=0; // 计数   
27.         **int** i\[\] = **new** **int**\[4\];   // 循环用 i\[0\] i\[1\] i\[2\] i\[3\]  
28.           
29.         **for**(i\[0\]=0;i\[0\]<4;i\[0\]++)\{   // (i=0,1,2,3) 0='+', 1='-', 2='\*', 3='/'  
30.             **if**(i\[0\]<3||num\[1\]!=0)\{  
31.                   
32.                 **for**(i\[1\]=0;i\[1\]<4;i\[1\]++)\{  
33.                     **if**(i\[1\]<3||num\[2\]!=0)\{  
34.                           
35.                         **for**(i\[2\]=0;i\[2\]<4;i\[2\]++)\{  
36.                             **if**(i\[2\]<3||num\[3\]!=0)\{  
37.                                   
38.                                 **for**(i\[3\]=0;i\[3\]<4;i\[3\]++)\{  
39.                                     **if**(i\[3\]<3||num\[4\]!=0)\{  
40.                                         **float** left = 0;  
41.                                         **float** right = num\[0\];  
42.                                         **int** sign = 1;   // 正负号  
43.                                         **for**(**int** j=0;j<4;j++)\{  
44.                                             **switch**(oper\[i\[j\]\])\{  
45.                                                 **case** '+':  
46.                                                     left = left+sign\*right;  
47.                                                     sign = 1;  
48.                                                     right = num\[j+1\];  
49.                                                     **break**;  
50.                                                 **case** '-':  
51.                                                     left = left+sign\*right;  
52.                                                     sign = -1;  
53.                                                     right = num\[j+1\];  
54.                                                     **break**;  
55.                                                 **case** '\*':  
56.                                                     right = right \* num\[j+1\];  
57.                                                     **break**;  
58.                                                 **case** '/':  
59.                                                     right = right / num\[j+1\];  
60.                                                     **break**;  
61.                                             \}  
62.                                         \}  
63.                                         **if**(left+sign\*right == result)\{  
64.                                             count++;  
65.                                             System.out.print(count+"：");  
66.                                             **for**(**int** j=0;j<4;j++)\{  
67.                                                 System.out.print(num\[j\]+""\+oper\[i\[j\]\]+"");  
68.                                             \}  
69.                                             System.out.println(num\[4\]+"="\+result);  
70.                                         \}  
71.                                     \}  
72.                                 \}  
73.                             \}  
74.                         \}  
75.                     \}  
76.                 \}  
77.             \}  
78.         \}  
79.         **if**(count==0)\{  
80.             System.out.println("没有符合要求的方法！");  
81.         \}  
82.     \}  
83. \}

**运行结果：**

![1354979262_7266.jpg][]

![1354979317_1758.jpg][]

[view plain]: http://blog.csdn.net/hanshileiai/article/details/8274055#
[1354979262_7266.jpg]: https://img-my.csdn.net/uploads/201212/08/1354979262_7266.jpg
[1354979317_1758.jpg]: https://img-my.csdn.net/uploads/201212/08/1354979317_1758.jpg