HDU5126---stars （CDQ套CDQ套 树状数组）

题意：Q次操作，三维空间内 每个星星对应一个坐标，查询以（x1,y1,z1） (x2,y2,z2)为左下顶点 、右上顶点的立方体内的星星的个数。

注意Q的范围为50000，显然离散化之后用三维BIT会MLE。 我们可以用一次CDQ把三维变成二维，变成二维之后就有很多做法了，树套树，不会树套树的话还可以继续CDQ由二维变成一维，，变成一维了就好做了，，最基本的数据结构题目了。。

不得不说、CDQ真的很神奇。

下面做法就是CDQ套CDQ套树状数组。

 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
 #include <algorithm>
 using namespace std;
 const int maxn = ;
 inline int lowbit (int x)
 {
     return x & -x;
 }
 int c[maxn*],MAX;
 void add(int x,int d)
 {
     while (x <= MAX)
     {
         c[x] += d;
         x += lowbit(x);
     }
 }
 int sum(int x)
 {
     int ans = ;
     while (x)
     {
         ans += c[x];
         x -= lowbit (x);
     }
     return ans;
 }
 struct Point
 {
     int x,y,z;
     int kind,idx,delt;
     Point() {}
     Point(int _x,int _y,int _z,int _delt,int _kind,int _idx):
         x(_x), y(_y), z(_z), delt(_delt), kind(_kind), idx(_idx) {}

 } star[maxn << ],star3[maxn << ];
 int ans[maxn<<];
 bool cmp1(const Point &p1,const Point &p2)
 {
     return p1.x < p2.x || ((p1.x == p2.x) && (p1.idx < p2.idx) );
 }
 bool cmp2(const Point &p1,const Point &p2)
 {
     return p1.y < p2.y || ((p1.y == p2.y) && (p1.idx < p2.idx) );
 }
 void CDQ2(int l,int r)
 {
     if (l >= r)
         return;
     int mid = (l + r) >> ;
     CDQ2(l,mid);
     CDQ2(mid+,r);
     int j = l;
     for (int i = mid + ; i <= r; i++)
     {
         if (star3[i].kind == )
         {
             for ( ; j <= mid  && (star3[j].y <= star3[i].y); j++)
             {
                 if (star3[j].kind == )
                     add(star3[j].z,star3[j].delt);
             }
             ans[star3[i].idx] += sum(star3[i].z) * star3[i].delt;
         }
     }
     for (int i = l; i < j; i++)
     {
         if (star3[i].kind == )
             add(star3[i].z,-star3[i].delt);
     }
     inplace_merge(star3+l,star3+mid+,star3+r+,cmp2);
 }
 void CDQ1(int l,int r)
 {
     if (l == r)
         return;
     int mid = (l + r) >> ;
     CDQ1(l, mid);
     CDQ1(mid+, r);
     int tot = ;
     for (int j = l; j <= mid ; j++)
         if (star[j].kind == )
             star3[tot++] = star[j];
     for (int i = mid + ; i <= r; i++)
     {
         if (star[i].kind == )
             star3[tot++] = star[i];
     }
     sort(star3+,star3+tot,cmp1);
     CDQ2(,tot-);
 }
 int vec[maxn << ],idx;
 void hash_(int tot)
 {
     sort(vec,vec+idx);
     idx = unique(vec,vec+idx) - vec;
     MAX = idx + ;
     for (int i = ; i <= tot; i++)
         star[i].z = lower_bound(vec,vec+idx,star[i].z) - vec + ;
 }
 int main(void)
 {
 #ifndef ONLINE_JUDGE
     freopen("in.txt","r",stdin);
 #endif // ONLINE_JUDGE
     int T,Q;
     scanf ("%d",&T);
     while (T--)
     {
         scanf ("%d",&Q);
         int tot = ;
         int totq = ;
         idx = ;
         memset(c,,sizeof (c));
         memset(ans,,sizeof(ans));
         for (int i = ; i <= Q; i++)
         {
             int op,x1,y1,z1,x2,y2,z2;
             scanf ("%d",&op);
             if (op == )
             {
                 scanf ("%d%d%d",&x1,&y1,&z1);
                 star[tot] = Point(x1,y1,z1,,,totq);
                 vec[idx++] = z1;
                 ans[totq] = -;
                 tot++;
                 totq++;
             }
             if (op == )
             {
                 scanf ("%d%d%d%d%d%d",&x1,&y1,&z1,&x2,&y2,&z2);
                 star[tot] = Point(x1-, y1-, z1-, -, , totq),  vec[idx++] = z1-, tot++;
                 star[tot] = Point(x2,   y1-, z1-,  , , totq),  vec[idx++] = z1-, tot++;
                 star[tot] = Point(x2 ,  y2  , z1-, -, , totq),  vec[idx++] = z1-, tot++;
                 star[tot] = Point(x1-, y2,   z1-,  , , totq),  vec[idx++] = z1-, tot++;
                 star[tot] = Point(x1-, y2,   z2  , -, , totq),  vec[idx++] = z2  , tot++;
                 star[tot] = Point(x2  , y2,   z2  ,  , , totq),  vec[idx++] = z2  , tot++;
                 star[tot] = Point(x2  , y1-, z2  , -, , totq),  vec[idx++] = z2  , tot++;
                 star[tot] = Point(x1-, y1-, z2  ,  , , totq),  vec[idx++] = z2  , tot++;
                 totq++;
             }
         }
         hash_(tot);
         CDQ1(,tot-);
         for (int i = ; i < totq; i++)
             if (~ans[i])
                 printf("%d\n",ans[i]);
     }
     return ;
 }