file transfer
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?
1 #include <stdio.h> 2 /* 3 测试用例1 4 5 5 C 3 2 6 I 3 2 7 C 1 5 8 I 4 5 9 I 2 4 10 C 3 5 11 S 12 测试用例2 13 5 14 C 3 2 15 I 3 2 16 C 1 5 17 I 4 5 18 I 2 4 19 C 3 5 20 I 1 3 21 C 1 5 22 S 23 */ 24 25 /* 集合的简化 */ 26 #define MaxSize 1000 27 typedef int ElementType; /*默认元素可以用非负整数表示*/ 28 typedef int SetName; /*默认用根结点的下标作为集合名称*/ 29 typedef ElementType SetType[MaxSize];/* 定义集合类型 */ 30 31 /* Initialization */ 32 void Initialization( SetType S , int n ) 33 { 34 int i; 35 for ( i=0; i<n; i++ ) S[i] = -1; 36 } 37 38 /* find */ 39 SetName Find( SetType S, ElementType X ) 40 { 41 if ( S[X] < 0 ) /* 找到集合的根 */ 42 return X; 43 else 44 return S[X] = Find( S, S[X] ); 45 /* 路径压缩： 46 先找到根, 47 把根变成 X 的父结点, 48 再返回根。 49 */ 50 } 51 52 /* union */ 53 void Union( SetType S, SetName Root1, SetName Root2 ) 54 { /* 按规模 比元素个数,少的贴多的 */ 55 if ( S[Root2]<S[Root1] ){ //负数,小即多 56 S[Root2] += S[Root1]; 57 S[Root1] = Root2; 58 } 59 else { 60 S[Root1] += S[Root2]; 61 S[Root2] = Root1; 62 } 63 /* 64 //按树高 比树高,矮树贴高树 65 if ( S[Root2] < S[Root1] ) 66 S[Root1] = Root2; 67 else { 68 if ( S[Root1]==S[Root2] ) S[Root1]--; 69 S[Root2] = Root1; 70 } */ 71 } 72 73 /* input */ 74 void Input_connection( SetType S ) 75 { 76 ElementType u, v; 77 SetName Root1, Root2; 78 scanf("%d %d ", &u, &v); 79 Root1 = Find(S, u-1); 80 Root2 = Find(S, v-1); 81 if ( Root1 != Root2 ) 82 Union( S, Root1, Root2 ); 83 } 84 85 /* check connection */ 86 void Check_connection( SetType S ) 87 { 88 ElementType u, v; 89 SetName Root1, Root2; 90 scanf("%d %d ", &u, &v); 91 Root1 = Find(S, u-1); 92 Root2 = Find(S, v-1); 93 if ( Root1 == Root2 ) 94 printf("yes "); 95 else printf("no "); 96 } 97 98 /* check network */ 99 void Check_network( SetType S, int n ) 100 { 101 int i, counter = 0; 102 for (i=0; i<n; i++) { 103 if ( S[i] < 0 ) counter++; 104 } 105 if ( counter == 1 ) 106 printf("The network is connected. "); 107 else 108 printf("There are %d components. ", counter); 109 } 110 111 /* 测试 */ 112 int main() 113 { 114 SetType S; 115 int n; 116 char in; 117 scanf("%d ", &n); 118 Initialization( S, n ); 119 do { 120 scanf("%c", &in); 121 switch (in) { 122 case 'I': Input_connection( S ); break; 123 case 'C': Check_connection( S ); break; 124 case 'S': Check_network( S, n ); break; 125 } 126 } while ( in != 'S'); 127 return 0; 128 }