kuangbin专题七 POJ3264 Balanced Lineup （线段树最大最小）

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 2

Sample Output

6
3
0



线段树维护最大最小，不涉及更改，只用pushup query就可以了

#include <iostream>
#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <algorithm>
#include <sstream>
#include <stack>
using namespace std;
#define FO freopen("in.txt","r",stdin);
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
#define debug(x) cout << "&&" << x << "&&" << endl;
#define lowbit(x) (x&-x)
#define mem(a,b) memset(a, b, sizeof(a));
typedef vector<int> VI;
typedef long long ll;
typedef pair<int,int> PII;
const ll mod=1000000007;
const int inf = 0x3f3f3f3f;
ll powmod(ll a,ll b) {ll res=1;a%=mod;for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
//head

const int maxn=200010;
int minn[maxn<<2],maxx[maxn<<2],n,q,a[maxn],maxpos,minpos;

void pushup(int rt) {
    minn[rt]=min(minn[rt<<1],minn[rt<<1|1]);
    maxx[rt]=max(maxx[rt<<1],maxx[rt<<1|1]);
}

void build(int rt,int L,int R){
    minn[rt]=0;
    maxx[rt]=0;
    if(L==R) {
        scanf("%d",&a[rt]);
        minn[rt]=maxx[rt]=a[rt];
        return;
    }
    int mid=(L+R)>>1;
    build(rt<<1,L,mid);
    build(rt<<1|1,mid+1,R);
    pushup(rt);
}

void query(int rt,int L,int R,int l,int r) {
    if(L>=l&&R<=r) {
        minpos=min(minpos,minn[rt]);
        maxpos=max(maxpos,maxx[rt]);
        return;
    }
    int mid=(L+R)>>1;
    if(l<=mid) query(rt<<1,L,mid,l,r);
    if(r>mid) query(rt<<1|1,mid+1,R,l,r);
}

int main() {
    while(~scanf("%d%d",&n,&q)) {
        build(1,1,n);
        int l,r;
        while(q--) {
            maxpos=-1,minpos=inf;
            scanf("%d%d",&l,&r);
            query(1,1,n,l,r);
            printf("%d\n",l==r?0:maxpos-minpos);
        }
    }
}