题解 | 小红的双排列删除得分

#include <bits/stdc++.h>
using namespace std;
using ll = long long int;
using ld = long double;
using PII=pair<ll,ll>;
using PIII=pair<int,pair<int,int>>;
const ld ESP = 1e-10;
const ld PI = acosl(-1);
const int N=1e5+10;
const int M=2e5+10;
// const int mod = 1000000007;
const int mod = 998244353;
//随机化
random_device rd;
mt19937 gen(rd());
uniform_int_distribution<> dis(1, 1000000000);
// cout<<fixed<<setprecision(10);


void solve(){
    int n;
    cin>>n;
    vector<array<int,2>> a(n+1);
    for(int i=1;i<=n;i++){
        a[i][0]=1e9;
        a[i][1]=0;
    }
    ll sum[2*n+10];
    int b[2*n+10];
    sum[0]=0;
    for(int i=1;i<=2*n;i++){
        int x;
        cin>>x;
        b[i]=x;
        a[x][0]=min(i,a[x][0]);
        a[x][1]=max(i,a[x][1]);
        sum[i]=sum[i-1]+x;
    }
    vector<ll> dp(2*n+10,0);
    ll ans=0;
    for(int i=1;i<=2*n;i++){
        if(i==a[b[i]][1]){
            dp[i]=max(dp[a[b[i]][0]-1]+sum[a[b[i]][1]]-sum[a[b[i]][0]-1],dp[i]);
        }
        dp[i]=max(dp[i-1],dp[i]);
        ans=max(dp[i],ans);
    }
    cout<<ans;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int _=1;
    // cin>>_;
    while(_--){
        solve();
    }
    return 0;
}