瞎搞-贪心-NOIP前44天-入门-家庭作业

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/TengWan_Alunl/article/details/82748941

使用并查集优化了一下贪心的查找，速度只需要那些用链表的时间的将近一半，Perfect。

#include<bits/stdc++.h>
#define rep(i,l,r) for(register int i=(l);i<=(r);i++)
#define per(i,r,l) for(register int i=(r);i>=(l);i--)
using namespace std;
const int inf=1e9+10,N=1e6+1000;
const double eps=1e-6;
struct homework{
	int time,credit;
	friend bool operator < (homework a,homework b){ return a.credit>b.credit; }
}a[N];
int n,ans,fa[N];
int getf(int v){ return fa[v]==v?v:fa[v]=getf(fa[v]);}
inline void merge(int a,int b){ fa[getf(b)]=fa[getf(a)];}
inline int read(){
	int v=0,f=1; char c;
	while(!isdigit(c=getchar())) if(c=='-') break;
	if(c=='-') f=0; else v=c-48;
	while(isdigit(c=getchar())) v=v*10+c-48;
	if(f) return v; else return -v;
}
int main(){
	rep(i,1,N-1) fa[i]=i;
	n=read();
	rep(i,1,n) a[i].time=read(),a[i].credit=read();
	sort(a+1,a+n+1);
	rep(i,1,n){
		int pos=getf(a[i].time); if(pos==0) continue;
		merge(pos-1,pos);
		ans+=a[i].credit;
	}
	printf("%d",ans);
	return 0;
}