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题目大意
有n个商品,利润为pi,在第di天之后过期,不包括di天。每天只能卖出一个商品。求最大的利润。
题目解析
优先安排利润高的商品,保证他能够卖出,但是希望他不要占据那么前的时间,这时才能给利润稍微没那么高的商品留出更多的选择余地,也就是说,利润次高的商品才能更有可能被选上。
优先先安排价格高的商品,最好是放在保质期d那一天。如果已经被占(商品价格肯定比它高),往前找。类似并查集找祖宗的过程。
AC code (并查集)
#include<iostream>
#include<queue>
#include<cstring>
#include<string>
#include<sstream>
#include<map>
#include<vector>
#include<cstdio>
#include<iostream>
#include<cmath>
#include<algorithm>
#include<cstdlib>
#include<stack>
#include<ctime>
using namespace std;
#define rep(i,aa,bb) for(register int i=aa;i<=bb;i++)
#define rrep(i,aa,bb) for(register int i=aa;i>=bb;i--)
#define mset(var,val) memset(var,val,sizeof(var))
#define LL long long
#define eps 0.000001
#define inf 0x7f7f7f7f
#define llinf 1e18
#define exp 0.000001
#define pai 3.141592654
#define random(x) rand()%(x)
#define lowbit(x) x&(-x)
inline int read()
{
int x=0,y=1;char a=getchar();while ( a>'9' || a<'0'){if ( a=='-')y=-1;a=getchar();}
while ( a>='0' && a<='9' ){ x=(x<<3)+(x<<1)+a-'0'; a=getchar();}return x*y;
}
#define N 10200
struct Node{
int p,d;
}q[N];int fa[N],n;
inline bool cmp(Node a,Node b){
return a.p > b.p ;
}
int findfa(int x){
if ( fa[x] == -1 ) return x;
return fa[x] = findfa(fa[x]);
}
int main()
{
freopen("1.txt","r",stdin);
while ( scanf("%d",&n) != EOF ){
mset(fa,-1);
rep(i,1,n)
scanf("%d%d",&q[i].p,&q[i].d);
int sum = 0;
sort(q+1,q+n+1,cmp);
rep(i,1,n){
int t = findfa(q[i].d);
if ( t > 0 ){
sum += q[i].p;
fa[ t ] = t-1;
}
}
cout<<sum<<endl;
}
return 0;
}
AC code (非并查集)
#include<iostream>
#include<queue>
#include<cstring>
#include<string>
#include<sstream>
#include<map>
#include<vector>
#include<cstdio>
#include<iostream>
#include<cmath>
#include<algorithm>
#include<cstdlib>
#include<stack>
#include<ctime>
using namespace std;
#define rep(i,aa,bb) for(register int i=aa;i<=bb;i++)
#define rrep(i,aa,bb) for(register int i=aa;i>=bb;i--)
#define mset(var,val) memset(var,val,sizeof(var))
#define LL long long
#define eps 0.000001
#define inf 0x7f7f7f7f
#define llinf 1e18
#define exp 0.000001
#define pai 3.141592654
#define random(x) rand()%(x)
#define lowbit(x) x&(-x)
inline int read()
{
int x=0,y=1;char a=getchar();while ( a>'9' || a<'0'){if ( a=='-')y=-1;a=getchar();}
while ( a>='0' && a<='9' ){ x=(x<<3)+(x<<1)+a-'0'; a=getchar();}return x*y;
}
#define N 10200
struct Node{
int p,d;
}q[N];int n;bool vis[N];
inline bool cmp(Node a,Node b){
return a.p > b.p ;
}
int main()
{
// freopen("1.txt","r",stdin);
while ( scanf("%d",&n) != EOF ){
mset(vis,0);
rep(i,1,n)
scanf("%d%d",&q[i].p,&q[i].d);
int sum = 0;
sort(q+1,q+n+1,cmp);
rep(i,1,n){
rrep(j,q[i].d,1){
if ( vis[j] == 0 ){
vis[ j ] = 1;
sum += q[i].p ;
break;
}
}
}
cout<<sum<<endl;
}
return 0;
}