hdu 4417 区间内比h小的数 划分树

二分查找最近一个比h小的数

 #include<cstdio>
 #include<iostream>
 #include<algorithm>
 #include<cstring>
 #include<cmath>
 #include<queue>
 using namespace std;
 #define for0n for(i=0;i<n;i++)
 #define for1n for(i=1;i<=n;i++)
 #define for0m for(i=0;i<m;i++)
 #define for1m for(i=1;i<=m;i++)
 #define cl(a) memset(a,0,sizeof(a))
 #define w12 while(scanf("%d%d",&n,&m)!=EOF)
 #define s12 scanf("%d%d",&n,&m);
 #define sa scanf("%d",a[i]);
 #define sb scanf("%d",b[i]);
 #define qq printf("*****\n");
 const int maxn=;
 int n,m,tt;
 const int MAXN = ;
 int tree[][MAXN];//表示每层每个位置的值
 int sorted[MAXN];//已经排序好的数
 int toleft[][MAXN];//toleft[p][i]表示第i层从1到i有数分入左边
 void build(int l,int r,int dep)
 {
     if(l == r)return;
     int mid = (l+r)>>;
     int same = mid - l + ;//表示等于中间值而且被分入左边的个数
     for(int i = l; i <= r; i++) //注意是l,不是one
     if(tree[dep][i] < sorted[mid])
     same--;
     int lpos = l;
     int rpos = mid+;
     for(int i = l;i <= r;i++)
     {
         if(tree[dep][i] < sorted[mid])
         tree[dep+][lpos++] = tree[dep][i];
         else if(tree[dep][i] == sorted[mid] && same > )
         {
             tree[dep+][lpos++] = tree[dep][i];
             same--;
         }
         else
         tree[dep+][rpos++] = tree[dep][i];
         toleft[dep][i] = toleft[dep][l-] + lpos - l;
     }
     build(l,mid,dep+);
     build(mid+,r,dep+);
 }
 //查询区间第k大的数,[L,R]是大区间，[l,r]是要查询的小区间
 int query(int L,int R,int l,int r,int dep,int k)
 {
     if(l == r)return tree[dep][l];
     int mid = (L+R)>>;
     int cnt = toleft[dep][r] - toleft[dep][l-];
     if(cnt >= k)
     {
         int newl = L + toleft[dep][l-] - toleft[dep][L-];
         int newr = newl + cnt - ;
         return query(L,mid,newl,newr,dep+,k);
     }
     else
     {
         int newr = r + toleft[dep][R] - toleft[dep][r];
         int newl = newr - (r-l-cnt);
         return query(mid+,R,newl,newr,dep+,k-cnt);
     }
 }
 int solve(int n,int s,int t,int h)
 {
     int l=;
     int r=(t-s)+;
     int ans=;
     while(l<=r)
     {
         int mid=((l+r)>>);
         int tp=query(,n,s,t,,mid);
         if(tp<=h)
         {
             ans=mid;
             l=mid+;
         }
         else r=mid-;
     }
     return ans;
 }
 int main()
 {
     #ifndef ONLINE_JUDGE
     freopen("1.in","r",stdin);
     #endif
     int i,j,k,h;
     scanf("%d",&tt);
     int ca=;
     while(tt--)
     {
         ca++;
         s12;
         memset(tree,,sizeof(tree));
         for(i = ;i <= n;i++)
         {
             scanf("%d",&tree[][i]);
             sorted[i] = tree[][i];
         }
         sort(sorted+,sorted+n+);
         build(,n,);
         int s,t,k;
         printf("Case %d:\n",ca);
         while(m--)
         {
             scanf("%d%d%d",&s,&t,&h);
             s++;
             t++;
             printf("%d\n",solve(n,s,t,h));
         }
     }
     return ;
 }