UESTC 电子科大专题训练 数据结构 A

Posted 2020-09-29 %%%%%

UESTC 1591

题意：求区间极值之差

思路：线段树裸题，不带更新

ACA代码：

#include "iostream"
#include "string.h"
#include "stack"
#include "queue"
#include "string"
#include "vector"
#include "set"
#include "map"
#include "algorithm"
#include "stdio.h"
#include "math.h"
#define ll long long
#define bug(x) cout<<x<<" "<<"UUUUU"<<endl;
#define mem(a) memset(a,0,sizeof(a))
#define mp(x,y) make_pair(x,y)
#define pb(x) push_back(x)
using namespace std;
const long long INF = 1e18+1LL;
const int inf = 1e9+1e8;
const int N=5e4+100;
const ll mod=1e9+7;

int mi[N<<2],ma[N<<2],maa,mii;
void push_up(int root){
    mi[root]=min(mi[root*2],mi[root*2+1]);
    ma[root]=max(ma[root*2],ma[root*2+1]);
}
void creat(int root, int l, int r){
    if(l==r){
        scanf("%d",&ma[root]);
        mi[root]=ma[root]; //cout<<l<<"UUUUUUUUUU"<<endl;
        return;
    }
    int mid=l+r>>1;
    creat(root*2, l, mid);
    creat(root*2+1, mid+1, r);
    push_up(root);
}
void query(int root,int l, int r, int L, int R){
    if(l==L && r==R){
        maa=max(maa,ma[root]), mii=min(mii,mi[root]);
        return;
    }
    int mid=l+r>>1;
    if(R<=mid) query(root*2, l, mid, L, R);
    else if(L>mid) query(root*2+1, mid+1, r, L, R);
    else{
        query(root*2, l, mid, L, mid);
        query(root*2+1, mid+1, r, mid+1, R);
    }
}
int main(){
    //ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
    int n,q,l,r;
    cin>>n>>q;
    creat(1,1,n);
    while(q--){
        scanf("%d%d",&l,&r);
        maa=-inf,mii=inf;
        query(1,1,n,l,r);
        printf("%d\n",maa-mii);
    }
    return 0;
}