codeforces 525 D Arthur and Walls

本文详细解析了Codeforces平台上的525D Arthur and Walls问题,包括问题背景、限制条件、解题思路以及提供了一段C++代码实现。重点介绍了如何通过2*2地考虑表格中'*'和'.'的分布,找出最少移除'*'以使'.'所在连通块成为矩形的方法。

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codeforces 525 D Arthur and Walls
题意:
给出一个n*m的表格,里面有'*'和'.',求把最少的'*'移除掉,使得'.'所在的连通块是矩形。

限制:
1 <= n,m <= 2000

思路:
2*2地考虑,如果2*2的格子里只有一个'*',说明这个'*'要去掉,其他情况都不用去掉。然后去掉这个'*'后,又会对其他四个格子有影响。
复杂度好难估计。

/*codeforces 525 D Arthur and Walls
  题意:
  给出一个n*m的表格,里面有'*'和'.',求把最少的'*'移除掉,使得'.'所在的连通块是矩形。
  限制:
  1 <= n,m <= 2000
  思路:
  2*2地考虑,如果2*2的格子里只有一个'*',说明这个'*'要去掉,其他情况都不用去掉。然后去掉这个'*'后,又会对其他四个格子有影响。
  复杂度好难估计。
 */
#include<iostream>
#include<cstdio>
using namespace std;
const int N=2005;
char str[N][N];
int n,m;
void gao(int x,int y){
	if(x==n-1 || y==m-1 || x<0 || y<0) return ;
	int tx,ty,s=0;
	for(int i=0;i<2;++i)
		for(int j=0;j<2;++j)
			if(str[x+i][y+j]=='*'){
				++s;
				tx=x+i;
				ty=y+j;
			}
	if(s==1){
		str[tx][ty]='.';
		for(int i=-1;i<1;++i)
			for(int j=-1;j<1;++j){
				gao(tx+i,ty+j);
			}
	}
}
int main(){
	scanf("%d%d",&n,&m);
	for(int i=0;i<n;++i)
		scanf("%s",str[i]);
	for(int i=0;i<n-1;++i)
		for(int j=0;j<m-1;++j){
			gao(i,j);
		}
	for(int i=0;i<n;++i)
		puts(str[i]);
	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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