Codeforces#552 div2 Shovels Shop

题意：从n个物品买k个，此时有m个优惠，对于一个一次性买了x个物品，可以免费这x中最便宜的y个物品。
思路：枚举取每种优惠最低值，dp

#include <bits/stdc++.h>
using namespace std;
#define ll long long 
#define forn(i,n) for(int i=0;i<n;i++)
#define for1(i,n) for(int i=1;i<=n;i++)
#define IO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0)
const int maxn = 2e5+5;
const ll INF = 0x3f3f3f3f3f3f3f3f;

int p[maxn];
ll dp[2005];

int main(){
    IO;
    ll n,m,k;cin>>n>>m>>k;
    vector<int>a(n);
    forn(i,n) cin>>a[i];
    sort(a.begin(),a.end());
    vector<ll>sum(k+1);
    sum[0] = 0;
    for1(i,k) sum[i] = a[i-1]+sum[i-1];
    a.resize(k);
    for1(i,m){
        int x,y;cin>>x>>y;
        p[x] = max(p[x],y);
    }
    for1(i,k) dp[i] = sum[i];
    for1(i,k){
        for1(j,i)if(p[j]){
            dp[i] = min(dp[i],dp[i-j]+sum[i]-sum[i-j+p[j]]);
        }
    }
    cout<<dp[k]<<'
';
    return 0;
}