Submission #1070424

#	Time	Username	Problem	Language	Result	Execution time	Memory
1070424		steveonalex	Building 4 (JOI20_building4)	C++17	0 / 100	2 ms	6540 KiB

building4

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
 
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
#define block_of_code if(true)
 
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(a, b);}
ll lcm(ll a, ll b){return a / gcd(a, b) * b;}
 
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
 
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
double rngesus_d(double l, double r){
    double cur = rngesus(0, MASK(60) - 1);
    cur /= MASK(60) - 1;
    return l + cur * (r - l);
}
 
template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b) {a = b; return true;}
        return false;
    }
 
template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b) {a = b; return true;}
        return false;
    }
 
template <class T>
    void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
        for(auto item: container) out << item << separator;
        out << finish;
    }
 
template <class T>
    void remove_dup(vector<T> &a){
        sort(ALL(a));
        a.resize(unique(ALL(a)) - a.begin());
    }

const int N = 1e6 + 69;
int a[2][N];
pair<int, int> dp[2][N];
 
int main(void){
    ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);
    clock_t start = clock();
 
    int n; cin >> n;
    for(int j = 0; j<=1; ++j)
    for(int i = 1; i<=n*2; ++i)
        cin >> a[j][i];
 
    dp[0][0] = dp[1][0] = {0, 0};
    for(int i= 1; i<=n*2; ++i){
        dp[0][i] = dp[1][i] = {-1, -1};
        for(int j = 0; j <= 1; ++j) if (dp[j][i-1].first != -1) {
            for(int k = 0; k <= 1; ++k) if (a[j][i-1] <= a[k][i]){
                pair<int, int> cur = dp[j][i-1];
                cur.first += k; cur.second += k;
                if (dp[k][i].first == -1) dp[k][i] = cur;
                else{
                    minimize(dp[k][i].first, cur.first);
                    maximize(dp[k][i].second, cur.second);
                }
            }
        }
    }
 
    int cu = -1;
    for(int j = 0; j <= 1; ++j){
        if (dp[j][n*2].first <= n && dp[j][n*2].second >= n){
            cu = j;
        }
    }
 
    if (cu == -1){
        cout << -1 << "\n";
        return 0;
    }
 
    string ans;
    int cnt = 0;
    for(int i = n*2; i>=1; --i){
        ans.push_back('A'+ cu);
        cnt += cu;
        for(int j = 0; j <= 1; ++j){
            if (dp[j][i-1].first + cnt <= n && dp[j][i-1].second + cnt >= n){
                cu = j;
                break;
            }
        }
    }

    reverse(ALL(ans));
    cout << ans << "\n";
 
    if (cnt != n) exit(1);
    int prev = 0;
    for(int i = 1; i<=n*2; ++i){
        int digit = ans[i-1] - 'A';
        if (a[digit][i] < prev) exit(1);
        prev = a[digit][i];
    }
 
 
 
    cerr << "Time elapsed: " << clock() - start << " ms\n";
    return 0;
}

• Subtask 1: 0 / 11
• Subtask 2: 0 / 89