poj 2528 动态线段树

动态建立结点就不用离散化了，细节见代码，相信还是比较好理解的。
  1 #include <iostream>
  2 #include <cstring>
  3 #include <cstdio>
  4 #include <set>
  5 using namespace std;
  6 
  7 const int N = 500000;
  8 set<int> s;
  9 int cnt;
 10 
 11 struct Node
 12 {
 13     int lc, rc, l, r, c;
 14     void init( int _l, int _r, int _c )
 15     {
 16         l = _l, r = _r, c = _c;
 17         lc = rc = -1;
 18     }
 19 } node[N << 2];
 20 
 21 void pushdown( int i )
 22 {
 23     if ( node[i].c != -1 )
 24     {
 25         node[node[i].lc].c = node[i].c;
 26         node[node[i].rc].c = node[i].c;
 27         node[i].c = -1;
 28     }
 29 }
 30 
 31 void update( int i, int l, int r, int c )
 32 {
 33     if ( node[i].l == l && node[i].r == r )
 34     {
 35         node[i].c = c;
 36         return ;
 37     }
 38     int mid = ( node[i].l + node[i].r ) >> 1;
 39     if ( node[i].lc == -1 )
 40     {
 41         node[i].lc = cnt;
 42         node[cnt].init( node[i].l, mid, -1 );
 43         cnt++;
 44     }
 45     if ( node[i].rc == -1 )
 46     {
 47         node[i].rc = cnt;
 48         node[cnt].init( mid + 1, node[i].r, -1 );
 49         cnt++;
 50     }
 51     pushdown(i);
 52     if ( r <= mid )
 53     {
 54         update( node[i].lc, l, r, c );
 55     }
 56     else if ( l > mid )
 57     {
 58         update( node[i].rc, l, r, c );
 59     }
 60     else
 61     {
 62         update( node[i].lc, l, mid, c );
 63         update( node[i].rc, mid + 1, r, c );
 64     }
 65 }
 66 
 67 void dfs( int i )
 68 {
 69     if ( node[i].c != -1 )
 70     {
 71         s.insert( node[i].c );
 72         return ;
 73     }
 74     if ( node[i].lc != -1 ) dfs( node[i].lc );
 75     if ( node[i].rc != -1 ) dfs( node[i].rc );
 76 }
 77 
 78 int main ()
 79 {
 80     int t;
 81     scanf("%d", &t);
 82     while ( t-- )
 83     {
 84         int n;
 85         scanf("%d", &n);
 86         node[0].init( 1, 10000000, -1 );
 87         cnt = 1;
 88         s.clear();
 89         for ( int i = 0; i < n; i++ )
 90         {
 91             int l, r;
 92             scanf("%d%d", &l, &r);
 93             if ( l > r ) swap( l, r );
 94             update( 0, l, r, i );
 95         }
 96         dfs(0);
 97         printf("%d
", s.size());
 98     }
 99     return 0;
100 }