Lunar New Year and Food Ordering

https://codeforces.com/contest/1106/problem/B

C++版本一

题解：

贪心

按价格排序，作为不足时的取菜顺序，设一个指针记录，如果指针到n+1，说明没有菜可以取了

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=100000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
ll t,n,m,k,q,d;
ll ans,cnt,flag,temp;
ll a[N];
ll c[N];
char str;
struct node{
    ll id,c;
    bool operator <(const node &S)const{
        return c<S.c;
    }
}e[N];
int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
    scanf("%I64d%I64d",&n,&m);
    for(int i=1;i<=n;i++){
        scanf("%I64d",&a[i]);
    }
    for(int i=1;i<=n;i++){
        scanf("%I64d",&e[i].c);
        e[i].id=i;
        c[i]=e[i].c;
    }
    sort(e+1,e+n+1);
    int pos=1;
    while(m--){
        scanf("%I64d%I64d",&t,&d);
        ans=0;
        if(a[t]>0){
            if(a[t]>=d){
                ans+=c[t]*d;
                a[t]-=d;
                d=0;
            }else{
                ans+=c[t]*a[t];
                d-=a[t];
                a[t]=0;
            }
        }
        while(d>0&&pos<=n){
//cout<<e[pos].id<<" "<<a[e[pos].id]<<d<<" "<<ans<<endl;
            if(a[e[pos].id]>0){
                if(a[e[pos].id]>=d){
                    ans+=c[e[pos].id]*d;
                    a[e[pos].id]-=d;
                    d=0;
                }else{
                    ans+=c[e[pos].id]*a[e[pos].id];
                    d-=a[e[pos].id];
                    a[e[pos].id]=0;
                    pos++;
                }
            }else{
                pos++;
            }

        }
        if(d>0){
            ans=0;
        }
        cout<<ans<<endl;
    }

    //cout << "Hello world!" << endl;
    return 0;
}

C++版本二

#include<stdio.h>
#include<stdlib.h>
#include<ctype.h>
#include<math.h>
#include<string.h>
#include<queue>
#include<algorithm>
#include<vector>
#define ll long long
#define pb push_back
#define INF 0x3f3f3f3f;
#define test printf("here!!!")
using namespace std;
const int mx=1e5+10;
const int mod=998244353;
struct Node
{
    int v;
    int id;
}hgf,dzb;
bool operator <(const Node &a,const Node &b)
{
    if (a.v!=b.v) return a.v>b.v;
    else return a.id>b.id;
}
priority_queue<Node>q;
int a[mx];
int c[mx];
int vis[mx];
int main()
{
    int n,m,t,d;
    scanf("%d%d",&n,&m);
    for (int i=1;i<=n;++i) scanf("%d",&a[i]);
    for (int i=1;i<=n;++i)
    {
        scanf("%d",&c[i]);
        hgf.v=c[i];
        hgf.id=i;
        q.push(hgf);
    }
    while (m--)
    {
        ll cost=0;
        scanf("%d%d",&t,&d);
        if (a[t]>=d)
        {
            a[t]-=d;
            cost=1ll*d*c[t];
            if (a[t]==0) vis[t]=1;
            d=0;
        }
        else
        {
            cost=1ll*a[t]*c[t];
            d-=a[t];
            a[t]=0;
            vis[t]=1;
            while (d&&!q.empty())
            {
                dzb=q.top();
                q.pop();
                if (a[dzb.id]>=d&&!vis[dzb.id])
                {
                    a[dzb.id]-=d;
                    cost+=1ll*d*dzb.v;
                    d=0;
                    if (a[dzb.id]==0) vis[dzb.id]=1;
                    else
                    {
                        q.push(dzb);
                    }
                }
                else if (a[dzb.id]<d&&!vis[dzb.id])
                {
                    cost+=1ll*a[dzb.id]*dzb.v;
                    d-=a[dzb.id];
                    a[dzb.id]=0;
                    vis[dzb.id]=1;
                }
            }
        }
        if (d) printf("0\n");
        else printf("%I64d\n",cost);
    }
}