HOJ 1007 SPF 求割点

  1 #include <stdio.h>
  2 #include <stdlib.h>
  3 
  4 bool arcs[1001][1001];
  5 bool visted[1001];
  6 int max_node;
  7 
  8 //traversal of Graph
  9 void DSF(int k); 
 10 
 11 int main()
 12 {
 13     int point_i, point_j;
 14     int acount = 1;
 15     int num_of_subnet;
 16     bool isnot;
 17 
 18     point_i = 1002;
 19     point_j = 1002;
 20 
 21     while (point_i != 0)
 22     {
 23         //Initial
 24         max_node = 0;
 25         for (int i=0; i<1001; i++)
 26         {
 27             for (int j=0; j<1001; j++)
 28             {
 29                 arcs[i][j] = false;
 30             }
 31         }
 32         //input
 33         if (point_i != 1002)
 34         {
 35             scanf("%d", &point_j);
 36             arcs[point_i][point_j] = true;
 37             arcs[point_j][point_i] = true;
 38             if (point_i > max_node)
 39             {
 40                 max_node = point_i;
 41             }
 42             if (point_j > max_node)
 43             {
 44                 max_node = point_j;
 45             }
 46         }
 47         while (scanf("%d", &point_i)==1 && point_i!=0)
 48         {    
 49             scanf("%d", &point_j);
 50             if (point_i > max_node)
 51             {
 52                 max_node = point_i;
 53             }
 54             if (point_j > max_node)
 55             {
 56                 max_node = point_j;
 57             }
 58             arcs[point_i][point_j] = true;
 59             arcs[point_j][point_i] = true;
 60         }
 61 
 62         //start reslove the problem here
 63         //If the graph is not a connected graph, there is no SPF node.
 64         isnot = true;
 65         for (int i=1; i<=max_node; i++)
 66         {
 67                 visted[i] = false;
 68         }
 69         DSF(1);
 70         for (int i=1; i<=max_node; i++)
 71         {
 72             if (visted[i] == false)
 73             {
 74                 if (acount  == 1)
 75                 {
 76                     printf("Network #%d\n", acount ++);
 77                 }
 78                 else
 79                 {
 80                     printf("\nNetwork #%d\n", acount ++);
 81                 }
 82                 goto here;
 83             }
 84         }
 85         //
 86         if (acount  == 1)
 87         {
 88             printf("Network #%d\n", acount ++);
 89         }
 90         else
 91         {
 92             printf("\nNetwork #%d\n", acount ++);
 93         }
 94         for (int i=1; i<=max_node; i++)
 95         {
 96             for (int j=1; j<=max_node; j++)
 97             {
 98                 visted[j] = false;
 99             }
100             visted[i] = true;
101             num_of_subnet = 0;
102             for (int k=1; k<=max_node; k++)
103             {
104                 if (!visted[k])
105                 {
106                     DSF(k);
107                     num_of_subnet ++;
108                 }
109             }
110             if (num_of_subnet > 1)
111             {
112                 isnot = false;
113                 printf("  SPF node %d leaves %d subnets\n", i, num_of_subnet);
114             }
115         }
116         if (isnot)
117         {
118 here:        printf("  No SPF nodes\n");
119         }
120 
121         scanf("%d", &point_i);
122     }
123 
124     return 0;
125 }
126 
127 void DSF(int k)
128 {
129     visted[k] = true;
130     for (int i=1; i<=max_node; i++)
131     {
132         if (arcs[k][i] && !visted[i])
133         {
134             DSF(i);
135         }
136     }
137 }

先前一直Time Limit Exceed，之后在求解之前加了对图的连通性的判断，终于AC了。不联通的图是没有割点的。