线段树，区间最值

CodeForces 91B Queue (线段树，区间最值)
题意是，对于给定区间内的每个元素，要求求出离他最远的那个元素之间的距离。
可以维护一个线段树的最小值，每次对于一个元素，查找其最右边的元素的位置。

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<unordered_map>
using namespace std;
const int maxn = 1e5+6;
struct node
{
int v;
int l,r;
}edge[4*maxn];
int a[maxn];
unordered_map<int,int> vis;
void build(int next,int x,int y)
{
	edge[next].l=x;
	edge[next].r=y;
   if(x==y)
   {
    edge[next].v=a[x];
   }
   else
   {
   int mid=(x+y)>>1;
   int next_left=(next<<1)+1;
   int next_rigth=(next<<1)+2;
   build(next_left,x,mid);
   build(next_rigth,mid+1,y);
   edge[next].v=min(edge[next_left].v,edge[next_rigth].v);
   }
}
int query(int next,int d)
{
   if(edge[next].l==edge[next].r) return edge[next].l;
   int mid=(edge[next].l+edge[next].r)>>1;
   int next_left=(next<<1)+1;
   int next_rigth=(next<<1)+2;
   if(edge[next_rigth].v<d) return query(next_rigth,d);  //从右边开始查找
   if(edge[next_left].v<d) return query(next_left,d);
}
int main()
{
	int n,m;
	scanf("%d",&n);
	for(int i=0;i<n;i++)
	{
	scanf("%d",&a[i]);
    }
    build(0,0,n-1);
    int h;
    for(int i=0;i<n;i++)
    {
	  if(i)
	  printf(" ");
	  if(edge[0].v<a[i])
	  h=query(0,a[i])-i-1;
	  else
	  h=-1;
	  if(h<0)
	  h=-1;
	  printf("%d",h);
	}
return 0;
}