1 #include <stdio.h>
2 #include <stdlib.h>
3
4 typedef int DataType;
5 //顺序队列：类型和界面函数声明
6 struct SeqQueue
7 {// 顺序队列类型定义
8 int MAXNUM; // 队列中最大元素个数
9 int f, r;
10 DataType *q;
11 };
12
13 typedef struct SeqQueue *PSeqQueue; // 顺序队列类型的指针类型
14
15 //创建一个空队列
16 PSeqQueue createEmptyQueue_seq(int m)
17 {
18 PSeqQueue queue = (PSeqQueue)malloc(sizeof(struct SeqQueue));
19 if (queue != NULL)
20 {
21 queue->q = (DataType*)malloc(sizeof(DataType) *m);
22 if (queue->q)
23 {
24 queue->MAXNUM = m;
25 queue->f = 0;
26 queue->r = 0;
27 return (queue);
28 }
29 else
30 free(queue);
31 }
32
33 printf("Out of space!!\n"); // 存储分配失败
34 return NULL;
35 }
36
37 //判断队列是否为空
38 int isEmptyQueue_seq(PSeqQueue queue)
39 {
40 return (queue->f == queue->r);
41 }
42
43 // 在队尾插入元素x，此队列队尾一个元素空出来
44 void enQueue_seq(PSeqQueue queue, DataType x)
45 {
46 if ((queue->r + 1) % queue->MAXNUM == queue->f)
47 printf("Full queue.\n");
48 else
49 {
50 queue->q[queue->r] = x;
51 queue->r = (queue->r + 1) % queue->MAXNUM;
52 }
53 }
54
55 // 删除队列头部元素
56 void deQueue_seq(PSeqQueue queue)
57 {
58 if (queue->f == queue->r)
59 printf("Empty Queue.\n");
60 else
61 queue->f = (queue->f + 1) % queue->MAXNUM;
62 }
63
64 DataType frontQueue_seq(PSeqQueue queue)
65 {
66 if (queue->f == queue->r)
67 {
68 printf("Empty Queue.\n");
69 return 0;
70 }
71 else
72 return (queue->q[queue->f]);
73 }
74
75
76 //个体状态判断函数
77
78 int farmer(int location)
79 {
80 //判断农夫的位置
81 return (0 != (location &0x08));
82 }
83
84 int wolf(int location)
85 {
86 //判断狼的位置
87 return (0 != (location &0x04));
88 }
89
90 int cabbage(int location)
91 {
92 //判断白菜的位置
93 return (0 != (location &0x02));
94 }
95
96 int goat(int location)
97 {
98 //判断羊的位置
99 return (0 != (location &0x01));
100 }
101
102 //安全状态的判断函数
103
104 // 若状态安全则返回true
105 int safe(int location)
106 {
107 // 羊吃白菜
108 if ((goat(location) == cabbage(location)) && (goat(location) != farmer(location)))
109 return 0;
110 // 狼吃羊
111 if ((goat(location) == wolf(location)) && (goat(location) != farmer(location)))
112 return 0;
113 return 1; // 其他状态是安全的
114 }
115
116 void bin_print(int num)
117 {
118 char tmp[4];
119 int i;
120 for (i = 0; i < 4; ++i)
121 {
122 tmp[i] = num & 0x01;
123 num >>= 1;
124 }
125 for (i = 3; i >= 0; --i)
126 putchar((tmp[i] == 0)?'0':'1');
127 return;
128 }
129
130 int main()
131 {
132
133 int i, movers, location, newlocation;
134 int route[16]; //用于记录已考虑的状态路径
135 PSeqQueue moveTo; //用于记录可以安全到达的中间状态
136
137 moveTo = createEmptyQueue_seq(20); //创建空队列
138 enQueue_seq(moveTo, 0x00); //初始状态进队列
139
140 for (i = 0; i < 16; i++)
141 route[i] = -1;
142
143 //准备数组route初值
144 route[0] = 0;
145
146 while (!isEmptyQueue_seq(moveTo) && (route[15] == - 1))
147 {
148 location = frontQueue_seq(moveTo); //取队头状态为当前状态
149 deQueue_seq(moveTo);
150
151 //考虑各种物品移动
152 for (movers = 1; movers <= 8; movers <<= 1)
153 //农夫与移动的物品在同一侧
154 if ((0 != (location & 0x08)) == (0 != (location & movers)))
155 {
156 newlocation = location ^ (0x08 | movers); //计算新状态
157
158 //新状态安全且未处理
159 if (safe(newlocation) && (route[newlocation] == -1))
160 {
161 route[newlocation] = location; //记录新状态的前驱
162 enQueue_seq(moveTo, newlocation); //新状态入队
163 }
164 }
165 }
166
167 // 打印出路径
168 if (route[15] != -1)
169 //到达最终状态
170 {
171 printf("The reverse path is : \n");
172
173 for (location = 15; location >= 0; location = route[location])
174 {
175 printf("The location is : %2d, ", location);
176 bin_print(location);
177 putchar('\n');
178 if (location == 0)
179 exit(0);
180 }
181 }
182 else
183 printf("No solution.\n");
184 return 0;
185 }
