luoguP1315 观光公交 题解(NOIP2011)(贪心)

P1315 观光公交 题目

#include<iostream>
#include<cstdlib>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<algorithm>
#include<iomanip>
#include<ctime>
#include<queue>
#include<stack>
#define rg register
#define lst long long
#define N 1050
#define M 10050
using namespace std;
 
int n,m,k,num[N],u,v,w;
int down[N],up[N],ans;
int arrive[N],peo[N];
int val,idx;
 
inline int read()
{
    rg int s=,m=;rg char ch=getchar();
    while(ch!='-'&&(ch<''||ch>''))ch=getchar();
    if(ch=='-')m=-,ch=getchar();
    while(ch>=''&&ch<='')s=(s<<)+(s<<)+ch-'',ch=getchar();
    return s*m;
}
 
int main()
{
//    freopen("s.in","r",stdin);
    n=read(),m=read(),k=read();
    for(rg int i=;i<n;++i)num[i]=read();
    for(rg int i=;i<=m;++i)
    {
        u=read(),v=read(),w=read();
        ans-=u,down[w]++,up[v]=max(u,up[v]);
    }
    while(k--)
    {
        memset(peo,,sizeof(peo));
        for(rg int i=;i<=n;++i)
            arrive[i]=max(arrive[i-],up[i-])+num[i-];
        for(rg int i=n;i>=;--i)
        {
            if(num[i-])
            {
                peo[i-]=down[i];
                if(arrive[i]>up[i])
                    peo[i-]+=peo[i];
            }
            else peo[i-]=;
        }
        val=,idx=-;
        for(rg int i=;i<=n;++i)
            if(val<peo[i])val=peo[i],idx=i;
        if(idx==-)break;
        num[idx]--;
    }
    for(rg int i=;i<=n;++i)
        arrive[i]=max(arrive[i-],up[i-])+num[i-];
    for(rg int i=;i<=n;++i)ans+=arrive[i]*down[i];
    printf("%d\n",ans);
    return ;
}