HDOJ 3790 最短路径问题 SPFA

因为没有对边判重，白白WA了好几次，注意输入时必须要对边判重

 

AC   187MS    8100K

 1 #include <queue>

 2 #include <stdio.h>

 3 #include <stdlib.h>

 4 #include <memory.h>

 5 using namespace std;

 6 

 7 const int maxn = 1001;

 8 const int INF = 0x3F3F3F3F;

 9 

10 int a, b, d, p, nNum, mNum;

11 int dist[maxn], px[maxn], QM[maxn];

12 int cost[maxn][maxn], g[maxn][maxn];

13 

14 void spfa(int sx, int tx)

15 {

16     int   xx;

17     queue <int> q;

18     

19     q.push(sx);

20     QM[sx]=1, dist[sx]=0, px[sx]=0;

21     

22     while (!q.empty())

23     {

24         xx = q.front();

25         q.pop();

26         QM[xx] = 0; /* Took Away */

27         

28         for (int i=1; i<=nNum; ++i)

29         {

30             if (dist[i] > dist[xx]+g[xx][i])

31             {

32                 dist[i] = dist[xx] + g[xx][i];

33                 px[i] = px[xx] + cost[xx][i];

34                 

35                 if (QM[i] == 0)

36                 {

37                     QM[i] = 1;

38                     q.push(i);

39                 }

40             }/* End of if */

41             else if (dist[i]==dist[xx]+g[xx][i]

42                     && px[i]>px[xx]+cost[xx][i])

43             {

44                 px[i] = px[xx] + cost[xx][i];

45             }

46         }/* End of For */

47     }/* End of While */

48     

49     printf("%d %d\n", dist[tx], px[tx]);

50 }/* spfa */

51 

52 int main()

53 {

54     while (~scanf("%d %d", &nNum, &mNum), nNum+mNum!=0)

55     {        

56         for (int i=1; i<=nNum; ++i)

57         {

58             QM[i] = 0;

59             px[i] = dist[i] = INF;

60             

61             for (int j=1; j<=nNum; ++j)

62                 g[i][j] = cost[i][j] = INF;

63         }/* End of For */

64         

65         for (int i=1; i<=mNum; ++i)

66         {

67             scanf("%d %d %d %d", &a, &b, &d, &p);

68             

69             if (d < g[a][b])  /* 判重 */ 

70             {

71                 g[a][b] = g[b][a] = d;

72                 cost[a][b] = cost[b][a] = p;

73             }    

74         }/* End of For */

75         

76         int sx, tx;

77         

78         scanf("%d %d", &sx, &tx);

79         spfa(sx, tx);

80     }/* End of While */

81     

82     return 0;

83 }