Submission #561164

#	Time	Username	Problem	Language	Result	Execution time	Memory
561164		Bill_00	Building 4 (JOI20_building4)	C++14	100 / 100	282 ms	29172 KiB

building4

#include <bits/stdc++.h>
#define N 500005
#define ff first
#define ss second
#define ll long long 
const ll MAXN = 1e9; 
using namespace std;

int n, a[2 * N], b[2 * N];
pair<int, int> dp[2 * N][2];

char x[2 * N];

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    
    cin >> n;
    for(int i = 1; i <= 2 * n; i++){
        cin >> a[i];
    }
    for(int i = 1; i <= 2 * n; i++){
        cin >> b[i];
    }

    dp[1][1] = {1, 1};
    dp[1][0] = {0, 0};
    for(int i = 2; i <= 2 * n; i++){
        dp[i][1] = {1e9, -1};
        dp[i][0] = {1e9, -1};
        if(a[i] >= a[i - 1]){
            dp[i][1].ff = min(dp[i][1].ff, dp[i - 1][1].ff + 1);
            dp[i][1].ss = max(dp[i][1].ss, dp[i - 1][1].ss + 1);
        }
        if(a[i] >= b[i - 1]){
            dp[i][1].ff = min(dp[i][1].ff, dp[i - 1][0].ff + 1);
            dp[i][1].ss = max(dp[i][1].ss, dp[i - 1][0].ss + 1);
        }
        if(b[i] >= a[i - 1]){
            dp[i][0].ff = min(dp[i][0].ff, dp[i - 1][1].ff);
            dp[i][0].ss = max(dp[i][0].ss, dp[i - 1][1].ss);
        }
        if(b[i] >= b[i - 1]){
            dp[i][0].ff = min(dp[i][0].ff, dp[i - 1][0].ff);
            dp[i][0].ss = max(dp[i][0].ss, dp[i - 1][0].ss);
        }
    }
    // for(int i = 1; i <= 2 * n; i++){
    //     cout << dp[i][1].ff << ' ' << dp[i][1].ss << '\n';
    //     cout << dp[i][0].ff << ' ' << dp[i][0].ss << '\n';
    // }
    if(dp[2 * n][0].ff <= n && n <= dp[2 * n][0].ss || dp[2 * n][1].ff <= n && n <= dp[2 * n][1].ss){
        int lol = n;
        deque<char> ans;
        for(int i = 2 * n; i >= 1; i--){
            if(dp[i][1].ff <= lol && lol <= dp[i][1].ss){
                if(ans.size() > 0){
                    if(ans.front() == 'A'){
                        if(a[i] > a[i + 1]){
                            ans.push_front('B');
                            continue;
                        }
                    }
                    else{
                        if(a[i] > b[i + 1]){
                            ans.push_front('B');
                            continue;
                        }
                    }
                }
                ans.push_front('A');
                lol--;
            }
            else{
                ans.push_front('B');
            }
        }
        for(char x : ans) cout << x;
    }
    else cout << -1;
}

Compilation message (stderr)

building4.cpp: In function 'int main()':
building4.cpp:53:29: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   53 |     if(dp[2 * n][0].ff <= n && n <= dp[2 * n][0].ss || dp[2 * n][1].ff <= n && n <= dp[2 * n][1].ss){
      |                             ^

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