【线段树查询区间最值】poj 3264 Balanced Lineup

 #include<cstdio>
 #include<algorithm>
 using namespace std;

 const int maxn=;
 struct Seg
 {
     int l,r,mi,ma;
 }tree[maxn*];
 int val[maxn];

 void build(int l,int r,int i=)
 {
     tree[i].l=l;
     tree[i].r=r;
     if (l==r)
     {
         tree[i].mi=val[l];
         tree[i].ma=val[l];
     }
     else
     {
         int mid=l+r>>;
         build(l,mid,i<<);
         build(mid+,r,i<<|);
         tree[i].mi=min(tree[i<<].mi,tree[i<<|].mi);
         tree[i].ma=max(tree[i<<].ma,tree[i<<|].ma);
     }
 }

 int querymi(int l,int r,int i=)
 {
     if (tree[i].l==l && tree[i].r==r) return tree[i].mi;
     int mid=tree[i].l+tree[i].r>>;
     if (r<=mid) return querymi(l,r,i<<);
     if (l>mid) return querymi(l,r,i<<|);
     return min(querymi(l,mid,i<<),querymi(mid+,r,i<<|));
 }

 int queryma(int l,int r,int i=)
 {
     if (tree[i].l==l && tree[i].r==r) return tree[i].ma;
     int mid=tree[i].l+tree[i].r>>;
     if (r<=mid) return queryma(l,r,i<<);
     if (l>mid) return queryma(l,r,i<<|);
     return max(queryma(l,mid,i<<),queryma(mid+,r,i<<|));
 }

 int main()
 {
     int n,m;
     scanf("%d%d",&n,&m);
     for (int i=;i<=n;i++) scanf("%d",&val[i]);
     build(,n);
     for (int i=;i<m;i++)
     {
         int l,r;
         scanf("%d%d",&l,&r);
         printf("%d\n",queryma(l,r)-querymi(l,r));
     }
     return ;
 }