pat 1003

方法一: dijstra + DFS

View Code

  1 #include <stdio.h>

  2 #include <string.h>

  3 

  4 const int INF = 10000000 ;

  5 int map[505][505];

  6 int dist[505];

  7 int teamNum[505];

  8 int visit[505];

  9 int N , M, C1, C2;

 10 int pathNum, maxTeamNum;

 11 void initApp()

 12 {

 13     int temp, m, n, i, j; 

 14     memset(visit, 0, sizeof(int)*505);

 15     for( i =0; i< N ;i++)

 16         for( j = 0; j< N; j++)

 17             if(i != j)

 18                 map[i][j] = map[j][i] = INF;

 19 

 20     //init the team number           

 21     for(i = 0; i< N; i++)

 22     {

 23         scanf("%d", &temp);

 24         teamNum[i] = temp;

 25     }

 26 

 27     //init the map

 28     for(m = 0; m < M; m++)

 29     {

 30         scanf("%d %d %d", &i, &j, &temp);

 31         map[i][j] = map[j][i] = temp;  

 32     }

 33 }

 34 void Dijkstra()

 35 {

 36     int i,j;

 37     for(i = 0; i < N; i++)

 38         dist[i] = map[C1][i];

 39     visit[C1] = 1;

 40 

 41     int min, minValue, value;

 42     for(i = 1; i < N; i++)

 43     {

 44         min = -1; minValue = INF;

 45 

 46         //find the next Node

 47         for(j = 0; j< N ;j++){

 48 

 49             if(visit[j] == 0 && dist[j] < minValue)

 50             {

 51                 minValue  = dist[j];

 52                 min = j;

 53             }

 54         }

 55         //no next node or has find the target node

 56         if(min == -1|| min == C2)

 57             break;

 58 

 59         //mark the node        

 60         visit[min] = 1;

 61         //update the distance information 

 62         for(j = 0; j < N; j++)

 63         {

 64             if(visit[j] == 0)

 65             {

 66                 value = dist[min] + map[min][j];

 67                 if(map[min][j] != INF && value < dist[j])

 68                     dist[j] = value;

 69 

 70             }

 71         }

 72 

 73     }    

 74 }

 75 void dfs(int currentId, int currentDis, int currentNum)

 76 {

 77     int i ;

 78     visit[currentId] = 1;

 79     //has find the destination

 80     if(currentId == C2)

 81     {

 82         if(currentDis == dist[C2])

 83         {

 84             pathNum++;

 85             if(currentNum > maxTeamNum)

 86             maxTeamNum = currentNum;

 87         }

 88         return;

 89     }

 90     //current distance has larger than  the length of the shortest path 

 91     if(currentDis > dist[C2])

 92         return ;

 93 

 94     for(i = 0; i< N; i++)

 95     {

 96         if(0 == visit[i] && map[currentId][i]!= INF)

 97         {

 98             dfs(i,currentDis+map[currentId][i],currentNum + teamNum[i] );

 99             visit[i] = 0;

100         }

101     }

102 

103 

104 }

105 int main(int argc, char *argv[])

106 {

107     int flag = 0;

108 

109     while(scanf("%d", &N)!= EOF){

110         

111         pathNum = 0;

112         maxTeamNum = 0;

113         scanf("%d %d %d", &M, &C1, &C2);

114         initApp();

115         Dijkstra();

116         memset(visit, 0 , sizeof(int)*505);

117         dfs(C1, 0, teamNum[C1]);

118     

119         if (flag == 0)

120             flag = 1;

121         else

122             printf("\n");

123 

124         printf("%d %d", pathNum, maxTeamNum);

125     }

126     

127     return 0;

128 }

 方法二： 改动后的dijstra

 方法二增加了两个数组，一个用来记录从源节点到当前节点路径的条数（pathNum[505]），一个用来记录从源节点到达当前节点的最大救援队的数目（maxTeamNum[]）

对方法的改动主要再三方面：

1）pathNum的初始化，源节点与当前节点联通时，初始化为一否则为零；maxTeamNum的初始化，源节点与当前节点联通时，初始化为源节点救援队的数目加上当前节点救援

队的数目，否则为零

2）找到下一个最短距离的点p对别的点进行更新时。当p点距离加上p到当前节点距离小于当前节点的最短距离时，更新当前节点的最短距离。并更新maxTeamNum 和 pathNum,pathNum

为p点的值，maxTeamNum 为p点的maxTeamNum+ 当前节点的teamNum

3)找到下一个最短距离的点p对别的点进行更新时。当p点距离加上p到当前节点距离等于于当前节点的最短距离时，更新当前节点的最短距离。并更新maxTeamNum 和 pathNum，当前节点的

pathNum = pathNum  + p点的pathNum； 当p点的maxTeamNum + 当前节点的teamNum 大于当前节点的maxTeamNum 时，更新当前节点的maxTeamNum

View Code

  1 #include <stdio.h>

  2 #include <string.h>

  3 

  4 const int INF = 10000000 ;

  5 int map[505][505];

  6 int dist[505];

  7 int teamNum[505],maxTeamNum[505],pathNum[505];

  8 int visit[505];

  9 int N , M, C1, C2;

 10 void initApp()

 11 {

 12     int temp, m, n, i, j; 

 13 

 14     memset(visit, 0, sizeof(int)*505);

 15     memset(maxTeamNum, 0, sizeof(int)*505);

 16     memset(pathNum, 0, sizeof(int)*505);

 17 

 18     for( i =0; i< N ;i++)

 19         for( j = 0; j< N; j++)

 20             if(i != j)

 21                 map[i][j] = map[j][i] = INF;

 22 

 23     //init the team number           

 24     for(i = 0; i< N; i++)

 25     {

 26         scanf("%d", &temp);

 27         teamNum[i] = temp;

 28     }

 29 

 30     //init the map

 31     for(m = 0; m < M; m++)

 32     {

 33         scanf("%d %d %d", &i, &j, &temp);

 34         map[i][j] = map[j][i] = temp;  

 35     }

 36 }

 37 void Dijkstra()

 38 {

 39     

 40     int i,j;

 41     int temp = teamNum[C1] ;

 42     

 43     //初始化距离与 路径条数 以及最大救援数目

 44     for(i = 0; i < N; i++)

 45     {

 46         dist[i] = map[C1][i];

 47         if(dist[i]!= INF)

 48         {

 49             pathNum[i] = 1;

 50             maxTeamNum[i] =teamNum[i]+  temp ;    

 51         }

 52     }

 53 

 54     dist[C1] = 0;

 55     maxTeamNum[C1] = temp;

 56     visit[C1] = 1;

 57 

 58     int min, minValue, value;

 59     for(i = 1; i < N; i++)

 60     {

 61         min = -1; minValue = INF;

 62 

 63         //find the next Node

 64         for(j = 0; j< N ;j++){

 65 

 66             if(visit[j] == 0 && dist[j] < minValue)

 67             {

 68                 minValue  = dist[j];

 69                 min = j;

 70             }

 71         }

 72         //no next node or has find the target node

 73         if(min == -1|| min == C2)

 74             break;

 75 

 76         //mark the node        

 77         visit[min] = 1;

 78         //update the distance information 

 79         for(j = 0; j < N; j++)

 80         {

 81             if(visit[j] == 0)

 82             {

 83                 value = dist[min] + map[min][j];

 84                 if(map[min][j] != INF && value < dist[j])

 85                 {

 86                     dist[j] = value;

 87                     maxTeamNum[j] = teamNum[j] + maxTeamNum[min];

 88                     pathNum[j] = pathNum[min] ;

 89                 }

 90                 else if(map[min][j] != INF && value == dist[j])

 91                 {

 92                     pathNum[j] += pathNum[min];

 93                     if(maxTeamNum[j] < teamNum[j] + maxTeamNum[min])

 94                         maxTeamNum[j] = teamNum[j] + maxTeamNum[min];

 95                 }

 96 

 97             }

 98         }

 99 

100     }    

101 }

102 int main(int argc, char *argv[])

103 {

104     int flag = 0;

105 

106     while(scanf("%d", &N)!= EOF){

107         

108         scanf("%d %d %d", &M, &C1, &C2);

109         initApp();

110         Dijkstra();

111         memset(visit, 0 , sizeof(int)*505);

112 

113         if (flag == 0)

114             flag = 1;

115         else

116             printf("\n");

117 

118         printf("%d %d", pathNum[C2], maxTeamNum[C2]);

119     }

120     

121     return 0;

122 }