codeforces1354D Multiset

本文探讨了一种使用树状数组实现的寻找第k小数的高效算法,通过优化读入过程,解决了处理大量数据和负数输入的问题。文章详细介绍了算法的实现细节,包括预处理、查找和更新操作。

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https://codeforces.com/problemset/problem/1354/D

这题直接用树状数组的找第k小数的一个log复杂度的方法做

然而之前t了一发。。。然后加读入优化后发现我之前自己的板子不能读负数。。。。尝试自己写后过了样例但是wa了。。。

后来网上抄了一个读入优化过了。。。

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define reads(n) FastIO::read(n)
namespace FastIO {
    const int SIZE = 1 << 16;
    char buf[SIZE], obuf[SIZE], str[60];
    int bi = SIZE, bn = SIZE, opt;
    int read(char *s) {
        while (bn) {
            for (; bi < bn && buf[bi] <= ' '; bi++);
            if (bi < bn) break;
            bn = fread(buf, 1, SIZE, stdin);
            bi = 0;
        }
        int sn = 0;
        while (bn) {
            for (; bi < bn && buf[bi] > ' '; bi++) s[sn++] = buf[bi];
            if (bi < bn) break;
            bn = fread(buf, 1, SIZE, stdin);
            bi = 0;
        }
        s[sn] = 0;
        return sn;
    }
    bool rd(int& x) {
        int n = read(str), bf;
        if (!n) return 0;
        int i = 0; if (str[i] == '-') bf = -1, i++; else bf = 1;
        for (x = 0; i < n; i++) x = x * 10 + str[i] - '0';
        if (bf < 0) x = -x;
        return 1;
    }
};
using namespace FastIO;
const int maxl=1e6+10;

int n,m,ans,cas,k,q;
int a[maxl],b[maxl];

inline int sum(int i)
{
	int ret=0;
	while(i)
	{
		ret+=b[i];
		i-=i&-i;
	}
	return ret;
}

inline void add(int i,int x)
{
	if(i==0) return;
	while(i<=n)
	{
		b[i]+=x;
		i+=i&-i;	
	}
}

inline void prework()
{
	//scanf("%d%d",&n,&q);
	rd(n);rd(q);
	for(register int i=1;i<=n;++i)
	{
		//scanf("%d",&a[i]);
		rd(a[i]);
		add(a[i],1);
	}
} 

inline int find_kth(int k)
{
    int ans=0,cnt=0;
    for (register int i=21;i>=0;--i)
    {
        ans+=(1<<i);
        if (ans>=n || cnt+b[ans]>=k)
            ans-=(1<<i);
        else
            cnt+=b[ans];
    }
    return ans+1;
}

inline void mainwork()
{
	int num=n,d;
	for(register int i=1;i<=q;++i)
	{
		//scanf("%d",&k);
		rd(k);
		if(k>0)
		{
			num++;
			add(k,1);
		}
		else
		{
			num--;
			d=find_kth(-k);
			add(d,-1);
		}
	}
	if(num==0)
		ans=0;
	else
		ans=find_kth(1);
}

inline void print()
{
	printf("%d",ans);
}

int main()
{
	int t=1;
	//scanf("%d",&t);
	for(cas=1;cas<=t;cas++)
	{
		prework();
		mainwork();
		print();
	}
	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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