這次的題讓我對選擇不同數據結構所產生的結果驚呆了，一開始用的是結構來存儲集合，課件上有現成的，而且我也是實在不太會，150ms的時間限制過不去，不得已，看到這題剛好可以用數組，結果7ms最多，有意思！什麼是時間復雜度，終於有了一次感性的認識。這題還有個check的要求，我用了一個鏈表來存儲，感覺挺麻煩的，不知是否有更好的方法，題設要求及代碼實現如下
1 /*
2 Name:
3 Copyright:
4 Author:
5 Date: 06/04/15 09:46
6 Description:
7 We have a network of computers and a list of bi-directional connections. Each of these connections allows a file transfer from one computer to another. Is it possible to send a file from any computer on the network to any other?
8
9 Input Specification:
10
11 Each input file contains one test case. For each test case, the first line contains N (2<=N<=104), the total number of computers in a network. Each computer in the network is then represented by a positive integer between 1 and N. Then in the following lines, the input is given in the format:
12
13 I c1 c2
14 where I stands for inputting a connection between c1 and c2; or
15
16 C c1 c2
17 where C stands for checking if it is possible to transfer files between c1 and c2; or
18
19 S
20 where S stands for stopping this case.
21
22 Output Specification:
23
24 For each C case, print in one line the word "yes" or "no" if it is possible or impossible to transfer files between c1 and c2, respectively. At the end of each case, print in one line "The network is connected." if there is a path between any pair of computers; or "There are k components." where k is the number of connected components in this network.
25
26 Sample Input 1:
27 5
28 C 3 2
29 I 3 2
30 C 1 5
31 I 4 5
32 I 2 4
33 C 3 5
34 S
35 Sample Output 1:
36 no
37 no
38 yes
39 There are 2 components.
40 Sample Input 2:
41 5
42 C 3 2
43 I 3 2
44 C 1 5
45 I 4 5
46 I 2 4
47 C 3 5
48 I 1 3
49 C 1 5
50 S
51 Sample Output 2:
52 no
53 no
54 yes
55 yes
56 The network is connected.
57 */
58 #include <stdio.h>
59 #include <stdlib.h>
60 #include <stdbool.h>
61
62 typedef struct Flag
63 {
64 bool flag;
65 struct Flag * next;
66 }Flag, * pFlag;
67
68 int Find(int S[], int X);
69 void Union(int S[], int X1, int X2);
70
71 int MaxSize;
72
73 int main()
74 {
75 // freopen("in.txt", "r", stdin); // for test
76 int i, c1, c2, k;
77 char ch;
78
79 scanf("%d\n", &MaxSize);
80
81 int S[MaxSize];
82 for(i = 0; i < MaxSize; i++)
83 S[i] = -1;
84
85 pFlag head = (pFlag)malloc(sizeof(Flag));
86 pFlag p, tmp;
87
88 p = head;
89 scanf("%c", &ch);
90 while(ch != 'S')
91 {
92 if(ch == 'C')
93 {
94 pFlag f = (pFlag)malloc(sizeof(Flag));
95 f->next = NULL;
96 scanf("%d%d\n", &c1, &c2);
97 if(Find(S, c1) == Find(S, c2))
98 f->flag = true;
99 else
100 f->flag = false;
101 p->next = f;
102 p = p->next;
103 }
104 else
105 {
106 scanf("%d%d", &c1, &c2);
107 Union(S, c1, c2);
108 }
109 scanf("%c", &ch);
110 }
111
112 p = head->next;
113 tmp = head;
114 free(tmp);
115 while(p)
116 {
117 if(p->flag)
118 printf("yes\n");
119 else
120 printf("no\n");
121 tmp = p;
122 p = p->next;
123 free(tmp);
124 }
125 k = 0;
126 do
127 {
128 if(S[--MaxSize] < 0)
129 k++;
130 }while(MaxSize);
131 if(k > 1)
132 printf("There are %d components.\n", k);
133 else
134 printf("The network is connected.\n");
135 // fclose(stdin); // for test
136 return 0;
137 }
138
139 int Find(int S[], int X)
140 {
141 X--;
142 for(; S[X] >= 0; X = S[X]);
143
144 return X;
145 }
146
147 void Union(int S[], int X1, int X2)
148 {
149 int Root1, Root2;
150
151 Root1 = Find(S, X1);
152 Root2 = Find(S, X2);
153 if(Root1 != Root2)
154 {
155 if(S[Root1] <= S[Root2])
156 {
157 S[Root1] += S[Root2];
158 S[Root2] = Root1;
159 }
160 else
161 {
162 S[Root2] += S[Root1];
163 S[Root1] = Root2;
164 }
165 }
166 }
