codeforces 765F Souvenirs

Posted 2020-09-01 MashiroSky

http://codeforces.com/problemset/problem/765/F (题目链接)

题意

　　给出$n$个数的序列，$m$次询问，每次查询区间$[l,r]$之间相差最小的两个数的差。

Solution

　　迷，右转题解→_→：jump

　　奇怪的线段树

细节

　　不造

代码

// codeforces 765F
#include<algorithm>
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<vector>
#include<cmath>
#include<ctime>
#define LL long long
#define inf 2147483640
#define Pi acos(-1.0)
#define free(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout)
using namespace std;

const int maxn=300010;
int n,Q,ans,a[maxn],res[maxn];
struct data {int l,r,id;}q[maxn];
struct node {int l,r,s;vector<int> v;}tr[maxn<<2];

bool cmp(data a,data b) {return a.r<b.r;}
void build(int k,int s,int t) {
	tr[k].l=s;tr[k].r=t;tr[k].s=inf;
	if (s==t) {tr[k].v.push_back(a[s]);return;}
	int mid=(s+t)>>1;
	build(k<<1,s,mid);build(k<<1|1,mid+1,t);
	int i=0,j=0,ll=tr[k<<1].v.size(),rr=tr[k<<1|1].v.size();
	while (i<ll || j<rr) {
		if ((i<ll && tr[k<<1].v[i]<tr[k<<1|1].v[j]) || j==rr)
			tr[k].v.push_back(tr[k<<1].v[i++]);
		else tr[k].v.push_back(tr[k<<1|1].v[j++]);
	}
	for (int i=1;i<=t-s;i++) tr[k].s=min(tr[k].s,tr[k].v[i]-tr[k].v[i-1]);
}
int query(int k,int s,int t) {
	int l=tr[k].l,r=tr[k].r,mid=(l+r)>>1;
	if (l==s && r==t) return tr[k].s;
	if (t<=mid) return query(k<<1,s,t);
	else if (s>mid) return query(k<<1|1,s,t);
	else return min(query(k<<1,s,mid),query(k<<1|1,mid+1,t));
}
void modify(int k,int p,int val) {
	int l=tr[k].l,r=tr[k].r,mid=(l+r)>>1;
	if (l==r) {tr[k].s=min(tr[k].s,abs(val-tr[k].v[0]));ans=min(ans,tr[k].s);return;}
	vector<int>::iterator t=lower_bound(tr[k].v.begin(),tr[k].v.end(),val);
	if (t==tr[k].v.end() || *t-val>=ans)
		if (t==tr[k].v.begin() || val-*--t>=ans) {ans=min(ans,tr[k].s);return;}
	if (p<=mid) modify(k<<1,p,val);
	else modify(k<<1|1,p,val),modify(k<<1,p,val);
	tr[k].s=min(tr[k].s,min(tr[k<<1].s,tr[k<<1|1].s));
}
int main() {
	scanf("%d",&n);
	for (int i=1;i<=n;i++) scanf("%d",&a[i]);
	scanf("%d",&Q);
	for (int i=1;i<=Q;i++) scanf("%d%d",&q[i].l,&q[i].r),q[i].id=i;
	sort(q+1,q+1+Q,cmp);
	build(1,1,n);
	int p=1;
	for (int i=1;i<=Q;i++) {
		while (p<q[i].r) ans=inf,modify(1,p,a[p+1]),p++;
		res[q[i].id]=query(1,q[i].l,q[i].r);
	}
	for (int i=1;i<=Q;i++) printf("%d\\n",res[i]);
	return 0;
}