简单拓扑排序

  1 //hdu 1285

  2 

  3 #include<stdio.h>

  4 #include<string.h>

  5 #include<stack>

  6 using namespace std;

  7 int map[600][600],n,count[600],seq[600],ff;

  8 int topo()

  9 {

 10     int i,j;

 11     ff=0;

 12     while(ff<n)//当为排完

 13     {

 14         for(i=1;i<=n;i++)//从小开始找

 15         {

 16             if(count[i]==0)//入读为0

 17             {

 18                 count[i]--;

 19                 seq[ff++]=i;

 20                 for(j=1;j<=n;j++)//相关的点减度

 21                     if(map[i][j])

 22                     {

 23                         count[j]--;

 24                     }

 25 

 26                 break;

 27             }

 28         }

 29     }

 30     return 1;

 31 }

 32 int main()

 33 {

 34     int i,j,m;

 35     while(scanf("%d%d",&n,&m)!=EOF)

 36     {

 37         ff=0;

 38         memset(count,0,sizeof(count));

 39         memset(map,0,sizeof(map));

 40         for(i=0;i<m;i++)

 41         {

 42             int x,y;

 43             scanf("%d%d",&x,&y);

 44             if(map[x][y]==0)//重边

 45             {

 46                 map[x][y]=1;

 47                 count[y]++;//入读

 48             }

 49         }

 50         int ans=topo();

 51         if(ans)

 52         {

 53             for(i=0;i<ff;i++)

 54                 if(i==0)printf("%d",seq[i]);

 55                 else printf(" %d",seq[i]);

 56                 printf("\n");

 57         }

 58     }

 59 }

 60 

 61 

 62 

 63 

 64 /*模版

 65 #include<stdio.h>

 66 #include<string.h>

 67 int map[103][103],n,m;

 68 int c[103];

 69 int dfs(int u)

 70 {

 71     int i,j,l;

 72     c[u]=-1;

 73     for(i=0;i<n;i++)

 74         if(map[u][i])

 75         {

 76             if(c[i]<0)

 77                 return 0;

 78             else if(!c[i]&&!dfs(i))

 79                 return 0;

 80         }

 81     c[u]=1;

 82     return 1;

 83 }

 84 int topo()

 85 {

 86     int i,j;

 87     memset(c,0,sizeof(c));

 88     for(i=0;i<n;i++)

 89     {

 90         if(!c[i])

 91             if(!dfs(i))

 92                 return 0;

 93     }

 94     return 1;

 95 }

 96 int main()

 97 {

 98     int i,j,l;

 99     while(scanf("%d%d",&n,&m)!=EOF)

100     {    

101         memset(map,0,sizeof(map));

102         if(!n)

103             break;

104         for(i=0;i<m;i++)

105         {

106             int a,b;

107             scanf("%d%d",&a,&b);

108             map[a][b]=1;

109         }

110         if(!topo())

111             printf("NO\n");

112         else printf("YES\n");

113     }

114 }*/