【csp模拟赛5】加减法--宽搜维护联通快

题目大意：

　　一开始想用并查集，发现很难维护联通块的代表元素，所以用了宽搜，开数组会炸，所以开一个优先队列维护，每扫完一个联通块，统计答案，清空优先队列，！！千万记住注意数组的大小！！！

代码：

#include<cstdio>
#include<iostream>
#include<cstdlib>
#include<algorithm>
#include<cstring>
#include<queue>
#define int long long
#define N 1005000
using namespace std;
int n,m,l,val[N],head[N],cnt,tot,ans;
int siz[N];
bool vis[N];
struct node{int to,nxt;}e[N];
int read()
{
	int x=0,f=1;
	char ch=getchar();
	while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
	while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
	return x*f;
}
void add(int from,int to)
{
	e[++cnt] = (node){to,head[from]};
	head[from]=cnt;
}
queue<int> q;
priority_queue <int> dij;
void bfs(int x)
{
	vis[x]=1;
	int siz=0;
	siz+=(val[x]-1);
	ans+=x;
	dij.push(x);
	q.push(x);
	while(!q.empty())
	{
		int s=q.front();
		q.pop();
		for(int i=head[s];i;i=e[i].nxt)
		{
			int y=e[i].to;
			if(!vis[y]){
				vis[y]=1;
				q.push(y);
				siz+=(val[y]-1);
				dij.push(y);
				ans+=y;
			}
		}
	}
	while(siz){
		int xx=dij.top(); dij.pop();
		if(siz<=l-1)
		{
			ans+=siz*xx;
			siz=0;
		}
		if(siz>(l-1))
		{
			siz-=(l-1);
			ans+=xx*(l-1);
		}
	}
	while(dij.size()) dij.pop();
}
signed main()
{
	#ifdef yilnr
	#else
	freopen("pmlaw.in","r",stdin);
	freopen("pmlaw.out","w",stdout);
	#endif
	n=read();m=read();l=read();
	for(int i=1;i<=n;i++)val[i]=read();
	for(int i=1,x,y;i<=m;i++)
	{
		scanf("%lld%lld",&x,&y);
		add(x,y);add(y,x);
	}
	for(int i=1;i<=n;i++)if(!vis[i])bfs(i);
	printf("%lld\n",ans);
	fclose(stdin);fclose(stdout);
	return 0;
}

原文地址：https://www.cnblogs.com/yelir/p/11564300.html