Submission #1134808

#	Time	Username	Problem	Language	Result	Execution time	Memory
1134808		dombly	Building 4 (JOI20_building4)	C++20	11 / 100	28 ms	4164 KiB

building4

#include <bits/stdc++.h>
#define int long long
#define F first
#define S second
#define pb push_back
using namespace std;
const int N = 5e5 + 10;
const int inf = 1e15;
const int mod = 1e9 + 7;

int a[N],b[N],dp[N][2][2];

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int n;
    cin >> n;
    n *= 2;
    for(int i = 1; i <= n; i++) cin >> a[i];
    for(int i = 1; i <= n; i++) cin >> b[i];
    vector<int> mna(n + 1, 1e9), mnb(n + 1, 1e9), mxa(n + 1, -1e9), mxb(n + 1, -1e9);
    mna[1] = mxa[1] = 1;
    mnb[1] = mxb[1] = -1;
    for(int i = 2; i <= n; i++) {
        if(a[i] >= a[i - 1]) {
            mxa[i] = max(mxa[i], mxa[i - 1]);
            mna[i] = min(mna[i], mna[i - 1]);
        }
        if(a[i] >= b[i - 1]) {
            mxa[i] = max(mxa[i], mxb[i - 1]);
            mna[i] = min(mna[i], mnb[i - 1]);
        }
        if(b[i] >= a[i - 1]) {
            mxb[i] = max(mxb[i], mxa[i - 1]);
            mnb[i] = min(mnb[i], mna[i - 1]);
        }
        if(b[i] >= b[i - 1]) {
            mxb[i] = max(mxb[i], mxb[i - 1]);
            mnb[i] = min(mnb[i], mnb[i - 1]);
        }
        mxa[i]++;
        mna[i]++;
        mxb[i]--;
        mnb[i]--;
    }
    if(min(mna[n], mnb[n]) > 0 || max(mxa[n], mxb[n]) < 0) {
        cout << -1;
        return 0;
    }
    int prv = inf,x = 0;
    string res;
    for(int i = n; i >= 1; i--) {
        if(a[i] > prv) {
            res += 'B';
            prv = b[i];
            x += 1;
            continue;
        }
        if(b[i] > prv) {
            res += 'A';
            prv = a[i];
            x -= 1;
            continue;
        }
        if(x >= mna[i] && x <= mxa[i]) {
            res += 'A';
            prv = a[i];
            x -= 1;
        }else {
            res += 'B';
            prv = b[i];
            x += 1;
        }
    }
    reverse(res.begin(),res.end());
    cout << res;
    return 0;
}

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