參考code

#include<bits/stdc++.h>
#define ll0 (ll)0
using namespace std;

typedef long long ll;

int main() {

    ll n; cin >> n;
    ll sum = 0;
    vector<ll> dp(n), v(n);
    for(int i = 0;i < n;i++) {
        cin >> v[i];
        sum += v[i];
    }
    if(n == 1) {
        cout << 0;
        return 0;
    }else if(n == 2) {
        cout << min(v[0], v[1]);
        return 0;
    }else if(n == 3) {
        cout << min(v[0] + v[2], v[1]);
        return 0;
    }
    dp[0] = v[0];
    dp[1] = v[1];
    dp[2] = max(ll0, v[0]) + v[2];

    ll ans = max({dp[0], dp[1], dp[2]});


    for(int i = 3;i < n;i++) {
        dp[i] = max(dp[i-2], dp[i-3]) + v[i];
        ans = max(ans, dp[i]);
    }

    cout << sum-ans;

    return 0;
}