hdu 5195 线段树

  1 #include<cstdio>
  2 #include<iostream>
  3 #include<algorithm>
  4 #include<cstring>
  5 #include<cmath>
  6 #include<queue>
  7 using namespace std;
  8 #define for0n for(i=0;i<n;i++)
  9 #define for1n for(i=1;i<=n;i++)
 10 #define w12 while(scanf("%d%d",&n,&m)!=EOF)
 11 #define cl(a) memset(a,0,sizeof(a))
 12 int n,m,t,Min;
 13 #define lson l,mid,rt<<1
 14 #define rson mid+1,r,rt<<1|1
 15 #define root 1,n,1
 16 #define mid ((l+r)>>1)
 17 const int MAXN=100010;
 18 const int INF = 0x3f3f3f3f;
 19 int head[MAXN],minn[MAXN<<2],in[MAXN];
 20 void pushup(int rt){
 21     minn[rt]=min(minn[rt<<1],minn[rt<<1|1]);
 22 }
 23 void build(int l,int r,int rt){
 24     if(l==r){
 25         minn[rt]=in[l];
 26         return;
 27     }
 28     build(lson);
 29     build(rson);
 30     pushup(rt);
 31 }
 32 int query(int k,int l,int r,int rt) {
 33     if(minn[rt]>k)  return -1;
 34     if (l==r)
 35     {
 36         return l;
 37     }
 38     if(minn[rt<<1|1]<=k)   return query(k,rson);
 39     if(minn[rt<<1]<=k)     return query(k,lson);
 40 }
 41 void update(int pos,int val,int l,int r,int rt)
 42 {
 43     if(l==r)    minn[rt]=val;
 44     else
 45     {
 46         if(pos<=mid)  update(pos,val,lson);
 47         else update(pos,val,rson);
 48         pushup(rt);
 49     }
 50 }
 51 struct Edge
 52 {
 53     int to,next;
 54 }edge[MAXN];
 55 int tot=0;
 56 void init()
 57 {
 58     tot=0;
 59     memset(head,-1,sizeof(head));
 60     cl(in);
 61 }
 62 void addedge(int u,int v)
 63 {
 64     edge[tot].to=v;
 65     edge[tot].next=head[u];
 66     head[u]=tot++;
 67 }
 68 int main()
 69 {
 70     int i,j,k;
 71     #ifndef ONLINE_JUDGE
 72     freopen("1.in","r",stdin);
 73     #endif
 74     while(scanf("%d%d%d",&n,&m,&k)!=EOF)
 75     {
 76         init();
 77         while(m--)
 78         {
 79             int u,v;
 80             scanf("%d%d",&u,&v);
 81             addedge(u,v);
 82             in[v]++;
 83         }
 84         build(root);
 85         for1n
 86         {
 87             int id=query(k,root);        //得到小于k的最大编号的结点
 88             k-=in[id];
 89             in[id]=INF;
 90             update(id,INF,root);
 91             for(j=head[id];j!=-1;j=edge[j].next)
 92             {
 93                 int v=edge[j].to;
 94                 in[v]--;
 95                 update(v,in[v],root);
 96             }
 97             printf("%d",id);
 98             if(i<n)printf(" ");
 99             else printf("\n");
100         }
101     }
102 }

2015-07-23：优先队列

  1 #include<cstdio>
  2 #include<iostream>
  3 #include<algorithm>
  4 #include<cstring>
  5 #include<cmath>
  6 #include<queue>
  7 #include<map>
  8 using namespace std;
  9 #define MOD 1000000007
 10 const int INF=0x3f3f3f3f;
 11 const double eps=1e-5;
 12 typedef long long ll;
 13 #define cl(a) memset(a,0,sizeof(a))
 14 #define ts printf("*****\n");
 15 const int MAXN=100010;
 16 int n,m,tt;
 17 priority_queue<int> q;
 18 vector<int> vc[MAXN];
 19 int in[MAXN];
 20 int head[MAXN];
 21 struct Edge
 22 {
 23     int to,next;
 24 }edge[MAXN];
 25 int tot=0;
 26 void init()
 27 {
 28     tot=0;
 29     memset(head,-1,sizeof(head));
 30     cl(in);
 31 }
 32 void addedge(int u,int v)
 33 {
 34     edge[tot].to=v;
 35     edge[tot].next=head[u];
 36     head[u]=tot++;
 37 }
 38 bool vis[MAXN];
 39 int main()
 40 {
 41     int i,j,k;
 42     #ifndef ONLINE_JUDGE
 43     freopen("1.in","r",stdin);
 44     #endif
 45     while(~scanf("%d%d%d",&n,&m,&k))
 46     {
 47         init();
 48         cl(in);
 49         cl(vis);
 50         bool flag=0;
 51         int u,v;
 52         for(i=1;i<=n;i++)
 53         {
 54             vc[i].clear();
 55         }
 56         for(i=0;i<m;i++)
 57         {
 58             scanf("%d%d",&u,&v);
 59             addedge(u,v);
 60             in[v]++;
 61             vc[u].push_back(v);
 62         }
 63         for(i=1;i<=n;i++)
 64         {
 65             if(in[i]<=k)
 66             {
 67                 q.push(i);
 68                 vis[i]=1;
 69             }
 70         }
 71         while(!q.empty())
 72         {
 73             int now=q.top();
 74             q.pop();
 75             if(k<in[now])
 76             {
 77                 vis[now]=0;
 78                 continue;
 79             }
 80             k-=in[now];
 81             for(i=0;i<vc[now].size();i++)
 82             {
 83                 int x=vc[now][i];
 84                 in[x]--;
 85                 if(!vis[x]&&in[x]<=k)
 86                 {
 87                     vis[x]=1;
 88                     q.push(x);
 89                 }
 90             }
 91             if(!flag)
 92             {
 93                 printf("%d",now);
 94                 flag=1;
 95             }
 96             else
 97                 printf(" %d",now);
 98         }
 99         printf("\n");
100     }
101 }