POJ1442-查询第K大-Treap模板题

  1 #include <cstdio>
  2 #include <algorithm>
  3 #include <cstring>
  4 
  5 using namespace std;
  6 
  7 const int maxn = 3e5+10;
  8 int num[maxn],st[maxn];
  9 
 10 struct Treap{
 11     int size;
 12     int key,fix;
 13     Treap *ch[2];
 14 
 15     Treap(int key)
 16     {
 17         size = 1;
 18         fix = rand();
 19         this->key = key;
 20         ch[0] = ch[1] = NULL;
 21     }
 22     int compare(int x) const
 23     {
 24         if(x == key) return -1;
 25         return x < key ? 0 : 1;
 26     }
 27     void Maintain()
 28     {
 29         size = 1;
 30         if(ch[0] != NULL) size += ch[0]->size;
 31         if(ch[1] != NULL) size += ch[1]->size;
 32     }
 33 };
 34 
 35 void Rotate(Treap* &t ,int d)
 36 {
 37     Treap *k = t->ch[d^1];
 38     t->ch[d^1] = k->ch[d];
 39     k->ch[d] = t;
 40     t->Maintain();
 41     k->Maintain();
 42     t = k;
 43 }
 44 
 45 void Insert(Treap* &t,int x)
 46 {
 47     if(t == NULL) t = new Treap(x);
 48     else
 49     {
 50         int d = x < t->key ? 0 : 1;
 51         Insert(t->ch[d],x);
 52         if(t->ch[d]->fix > t->fix)
 53             Rotate(t,d^1);
 54     }
 55     t->Maintain();
 56 }
 57 
 58 void Delete(Treap* &t,int x)
 59 {
 60     int d = t->compare(x);
 61     if(d == -1)
 62     {
 63         Treap *tmp = t;
 64         if(t->ch[0] == NULL)
 65         {
 66             t = t->ch[1];
 67             delete tmp;
 68             tmp = NULL;
 69         }
 70         else if(t->ch[1] == NULL)
 71         {
 72             t = t->ch[0];
 73             delete tmp;
 74             tmp = NULL;
 75         }
 76         else
 77         {
 78             int k = t->ch[0]->fix > t->ch[1]->fix ? 1 : 0;
 79             Rotate(t,k);
 80             Delete(t->ch[k],x);
 81         }
 82     }
 83     else Delete(t->ch[d],x);
 84     if(t!=NULL) t->Maintain();
 85 }
 86 
 87 bool Find(Treap *t,int x)
 88 {
 89     while(t != NULL)
 90     {
 91         int d = t->compare(x);
 92         if(d == -1) return true;
 93         t = t->ch[d];
 94     }
 95     return false;
 96 }
 97 
 98 int Kth(Treap *t,int k)
 99 {
100     if(t == NULL || k <= 0 || k > t->size)
101         return -1;
102     if(t->ch[0] == NULL && k == 1)
103         return t->key;
104     if(t->ch[0] == NULL)
105         return Kth(t->ch[1],k-1);
106     if(t->ch[0]->size >= k)
107         return Kth(t->ch[0],k);
108     if(t->ch[0]->size + 1 == k)
109         return t->key;
110     return Kth(t->ch[1],k-1-t->ch[0]->size);
111 }
112 
113 int Rank(Treap *t,int x)
114 {
115     int r;
116     if(t->ch[0] == NULL) r = 0;
117     else r = t->ch[0]->size;
118     if(x == t->key) return r+1;
119     if(x < t->key)
120         return Rank(t->ch[0],x);
121     return r+1+Rank(t->ch[1],x);
122 }
123 
124 void DeleteTreap(Treap* &t)
125 {
126     if(t == NULL) return;
127     if(t->ch[0] != NULL) DeleteTreap(t->ch[0]);
128     if(t->ch[1] != NULL) DeleteTreap(t->ch[1]);
129     delete t;
130     t = NULL;
131 }
132 
133 int save[maxn];
134 int M,N;
135 
136 int main()
137 {
138     while(~scanf("%d%d",&M,&N))
139     {
140         for(int i=1;i<=M;i++)
141             scanf("%d",&save[i]);
142         Treap *root = NULL;
143         int cnt = 1;
144         for(int i=1,x;i<=N;i++)
145         {
146             scanf("%d",&x);
147             for(int j = cnt;j <= x;j++)
148                 Insert(root,save[j]);
149             cnt = x+1;
150             printf("%d\n",Kth(root,i));
151         }
152         DeleteTreap(root);
153     }
154 }