3277-City Horizon

来源：互联网发布：松下fp系列编程手册编辑：程序博客网时间：2024/04/29 17:44
(http://poj.org/problem?id=3277)
#include <iostream>  #include <algorithm>  using namespace std;  const int Max = 40000;  // 对象  struct Shadow {      int b, e, h;  }s[Max];  struct TreeNode {      int l, r;      int c;  }tree[2*Max*4];  int p[2*Max]; // 离散化向量  long long area;  // 函数  bool cmp_for_s( const Shadow & s1, const Shadow & s2 )  {      return s1.h < s2.h;  }  //-----------------离散化查找-------------------//  int BS( int l, int r, const int key )  {      while( l <= r ) {          int mid = ( l + r ) >> 1;          if( key == p[mid] )              return mid + 1;          else if( key < p[mid] )               r = mid - 1;          else              l = mid + 1;      }      return 0; // 未找到  }  //-----------------线段树操作-------------------//  void Build( const int l, const int r, const int id )  {      tree[id].l = l;      tree[id].r = r;      tree[id].c = 0;      if( r - l == 1 ) return;      int mid = ( l + r ) >> 1;      Build( l, mid, id * 2 );      Build( mid, r, id * 2 + 1 );  }  void Update( const int l, const int r, const int h, const int id )  {      if( tree[id].l == l && tree[id].r == r )     {          tree[id].c = h;          return;      }      if( tree[id].c > 0 )    {          tree[ id*2 ].c = tree[ id*2+1 ].c = tree[id].c;          tree[id].c = 0;      }      int mid = ( tree[id].l + tree[id].r ) >> 1;      if( r <= mid )           Update( l, r, h, id * 2 ); // 注意啊, 注意啊 // 开始写成了 Update( l, mid, ... )      else if( l >= mid )           Update( l, r, h, id * 2 + 1 ); // 同样注意      else     {          Update( l, mid, h, id * 2 );          Update( mid, r, h, id * 2 + 1 );      }  }  void Query( const int id )  {      if( tree[id].c > 0 )     { // 该死的中间结果溢出，测试时已经发现不对劲了。。          area += ( p[ tree[id].r-1 ] - p[ tree[id].l-1 ] ) * ( long long )tree[id].c;          return;      }      if( tree[id].r - tree[id].l == 1 ) return;      Query( id * 2 );      Query( id * 2 + 1 ); }  //-------------------------end---------------------------//  int main()  {      int N;      scanf( "%d", & N );      int len = 0;      for( int i = 0; i < N; ++ i )     {          scanf( "%d%d%d", & s[i].b, & s[i].e, & s[i].h );          p[ len++ ] = s[i].b;          p[ len++ ] = s[i].e;      }      // 离散化      //::sort( p, p + 2 * N );      ::sort( s, s + N, ::cmp_for_s );      // 建树      ::Build( 1, 2 * N, 1 );      // 覆盖      for( int i = 0; i < N; ++ i )     {          int l = ::BS( 0, 2 * N - 1, s[i].b );          int r = ::BS( 0, 2 * N - 1, s[i].e );          Update( l, r, s[i].h, 1 );          /*Show( 1 );*/      }      // 遍历树      area = 0;      ::Query( 1 );  //::表示该函数是全局作用域     printf( "%lld", area );       return 0;  }
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