CodeForces 475D CGCDSSQ

本文介绍了一种针对区间GCD查询的高效算法,通过预处理和数据结构优化实现nlogn的时间复杂度,适用于大量查询场景。文章提供了一个具体的实现案例,并对比了相似题目,如HDU5726。

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Description

Given a sequence of integers a1, ..., an and q queries x1, ..., xq on it. For each query xi you have to count the number of pairs (l, r)such that 1 ≤ l ≤ r ≤ n and gcd(al, al + 1, ..., ar) = xi.

 is a greatest common divisor of v1, v2, ..., vn, that is equal to a largest positive integer that divides all vi.

Input

The first line of the input contains integer n, (1 ≤ n ≤ 105), denoting the length of the sequence. The next line contains n space separated integers a1, ..., an, (1 ≤ ai ≤ 109).

The third line of the input contains integer q, (1 ≤ q ≤ 3 × 105), denoting the number of queries. Then follows q lines, each contain an integer xi, (1 ≤ xi ≤ 109).

Output

For each query print the result in a separate line.

Sample Input

Input
3
2 6 3
5
1
2
3
4
6
Output
1
2
2
0
1
Input
7
10 20 3 15 1000 60 16
10
1
2
3
4
5
6
10
20
60
1000
Output
14
0
2
2
2
0
2
2
1

1

求所有区间的gcd的值,对于以i为右端点的全部gcd的种类一定是log(a[i])级别的,

往这些区间里再加上a[i+1],再把相同的区间合并,就可以保证全部的效率是nlogn了。

顺便一提,HDU5726和这题几乎一模一样,那题我用了线段树,时间上要多一个log

我就说怎么大家都会写,原来cf上有过类似的题目啊。

#include<set>
#include<map>
#include<ctime>
#include<cmath>
#include<stack>
#include<queue>
#include<bitset>
#include<cstdio>
#include<string>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<functional>
#define rep(i,j,k) for (int i = j; i <= k; i++)
#define per(i,j,k) for (int i = j; i >= k; i--)
#define loop(i,j,k) for (int i = j;i != -1; i = k[i])
#define lson x << 1, l, mid
#define rson x << 1 | 1, mid + 1, r
#define fi first
#define se second
#define mp(i,j) make_pair(i,j)
#define pii pair<int,int>
using namespace std;
typedef long long LL;
const int low(int x) { return x&-x; }
const double eps = 1e-4;
const int INF = 0x7FFFFFFF;
const int mod = 9973;
const int N = 3e5 + 10;
map<int, LL> M;
int n, x;

int gcd(int x, int y)
{
	return x%y ? gcd(y, x%y) : y;
}

int main()
{
	scanf("%d", &n);
	stack<pii> a, b;
	rep(i, 1, n)
	{
		scanf("%d", &x);  a.push(mp(x, 1));
		while (!a.empty()) b.push(mp(gcd(a.top().fi, x), a.top().se)), a.pop();
		while (!b.empty())
		{
			pii q = b.top();	b.pop();
			M[q.fi] += q.se;
			if (!a.empty() && a.top().fi == q.fi) q.se += a.top().se, a.pop();
			a.push(q);
		}
	}
	scanf("%d", &n);
	while (n--)
	{
		scanf("%d", &x);
		printf("%lld\n", M[x]);
	}
	return 0;
}


### Codeforces 1487D Problem Solution The problem described involves determining the maximum amount of a product that can be created from given quantities of ingredients under an idealized production process. For this specific case on Codeforces with problem number 1487D, while direct details about this exact question are not provided here, similar problems often involve resource allocation or limiting reagent type calculations. For instance, when faced with such constraints-based questions where multiple resources contribute to producing one unit of output but at different ratios, finding the bottleneck becomes crucial. In another context related to crafting items using various materials, it was determined that the formula `min(a[0],a[1],a[2]/2,a[3]/7,a[4]/4)` could represent how these limits interact[^1]. However, applying this directly without knowing specifics like what each array element represents in relation to the actual requirements for creating "philosophical stones" as mentioned would require adjustments based upon the precise conditions outlined within 1487D itself. To solve or discuss solutions effectively regarding Codeforces' challenge numbered 1487D: - Carefully read through all aspects presented by the contest organizers. - Identify which ingredient or component acts as the primary constraint towards achieving full capacity utilization. - Implement logic reflecting those relationships accurately; typically involving loops, conditionals, and possibly dynamic programming depending on complexity level required beyond simple minimum value determination across adjusted inputs. ```cpp #include <iostream> #include <vector> using namespace std; int main() { int n; cin >> n; vector<long long> a(n); for(int i=0;i<n;++i){ cin>>a[i]; } // Assuming indices correspond appropriately per problem statement's ratio requirement cout << min({a[0], a[1], a[2]/2LL, a[3]/7LL, a[4]/4LL}) << endl; } ``` --related questions-- 1. How does identifying bottlenecks help optimize algorithms solving constrained optimization problems? 2. What strategies should contestants adopt when translating mathematical formulas into code during competitive coding events? 3. Can you explain why understanding input-output relations is critical before implementing any algorithmic approach? 4. In what ways do prefix-suffix-middle frameworks enhance model training efficiency outside of just tokenization improvements? 5. Why might adjusting sample proportions specifically benefit models designed for tasks requiring both strong linguistic comprehension alongside logical reasoning skills?
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