Description
For the daily milking, Farmer John's N cows (1 ≤ N ≤ 50,000) always line up in the same order. One day Farmer John decides to organize a game of Ultimate Frisbee with some of the cows. To keep things simple, he will take a contiguous range of cows from the milking lineup to play the game. However, for all the cows to have fun they should not differ too much in height.
Farmer John has made a list of Q (1 ≤ Q ≤ 200,000) potential groups of cows and their heights (1 ≤ height ≤ 1,000,000). For each group, he wants your help to determine the difference in height between the shortest and the tallest cow in the group.
Input
Line 1: Two space-separated integers, N and Q. Lines 2.. N+1: Line i+1 contains a single integer that is the height of cow i Lines N+2.. N+ Q+1: Two integers A and B (1 ≤ A ≤ B ≤ N), representing the range of cows from A to B inclusive.Output
Lines 1.. Q: Each line contains a single integer that is a response to a reply and indicates the difference in height between the tallest and shortest cow in the range.Sample Input
6 3 1 7 3 4 2 5 1 5 4 6 2 2Sample Output
6 3 0Source
USACO 2007 January Silver
题意很简单，就不翻译了。
此题数据量非常大，简单的模拟必然会超时，线段树是个不错的选择
我们可以通过线段树分别查找区间最大值和区间最小值，之差就是答案了。。
Source Code
Problem: 3264 User: bingshenMemory: 2384K Time: 1954MSLanguage: C++ Result: Accepted Source Code #include<stdio.h> #include<string.h> struct node { int max; int min; int l; int r; }; node tree[200000]; int h[50005]; int max,min; int MAX(int a,int b) { if(a>b) return a; else return b; } int MIN(int a,int b) { if(a>b) return b; else return a; } void build(int l,int r,int root) { tree[root].l=l; tree[root].r=r; if(l==r) { tree[root].max=h[l]; tree[root].min=h[l]; return; } int mid=(l+r)>>1; build(l,mid,root*2); build(mid+1,r,root*2+1); tree[root].max=MAX(tree[2*root].max,tree[2*root+1].max); tree[root].min=MIN(tree[2*root].min,tree[2*root+1].min); } void findmax(int l,int r,int root) { if(tree[root].l==l&&tree[root].r==r) { if(tree[root].max>max) max=tree[root].max; return; } int mid=(tree[root].l+tree[root].r)>>1; if(mid>=r) findmax(l,r,root*2); else if(mid<l) findmax(l,r,root*2+1); else { findmax(l,mid,root*2); findmax(mid+1,r,root*2+1); } } void findmin(int l,int r,int root) { if(tree[root].l==l&&tree[root].r==r) { if(tree[root].min<min) min=tree[root].min; return; } int mid=(tree[root].l+tree[root].r)>>1; if(mid>=r) findmin(l,r,root*2); else if(mid<l) findmin(l,r,root*2+1); else { findmin(l,mid,root*2); findmin(mid+1,r,root*2+1); } } int main() { int n,q,i,a,b; scanf("%d%d",&n,&q); for(i=1;i<=n;i++) scanf("%d",&h[i]); build(1,n,1); while(q--) { max=0; min=99999999; scanf("%d%d",&a,&b); findmax(a,b,1); findmin(a,b,1); printf("%d/n",max-min); } return 0; } 果断的1Y，很久没这个感觉了。。
