Submission #1129971

#	Time	Username	Problem	Language	Result	Execution time	Memory
1129971		Ludissey	Alternating Current (BOI18_alternating)	C++20	13 / 100	753 ms	1114112 KiB

alternating

#include <bits/stdc++.h>
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
 
using namespace std;

vector<pair<pair<int,int>,int>> edge;
vector<vector<vector<int>>> memo;
vector<vector<vector<int>>> place;
int l=0;
int l2=0;
int n,m; 

bool dp(int i, int r, int r2){
    if(memo[i][r][r2]>-1) return memo[i][r][r2];
    if(i==m){
        if(r-l>=n-1&&r2-l2>=n-1) return 1;
        return 0;
    }
    bool tk=false;
    bool ntk=false;
    if(edge[i].first.first-1<=r){
        tk=dp(i+1,max(edge[i].first.second,r),r2);
    }
    if(edge[i].first.first-1<=r2){
        ntk=dp(i+1,r,max(edge[i].first.second,r2));
    }
    if(tk) place[i][r][r2]=0;
    else if(ntk) place[i][r][r2]=1;
    return (memo[i][r][r2]=max(tk,ntk));
}

vector<int> out;

void prnt(int i, int r, int r2){
    if(i>=m) return;
    out[edge[i].second]=place[i][r][r2];

    if(place[i][r][r2]==0){
        prnt(i+1,max(edge[i].first.second,r),r2);
    }else{
        prnt(i+1,r,max(edge[i].first.second,r2));
    }
    return;
}


signed main() {
    ios_base::sync_with_stdio(false); cin.tie(nullptr);
    cin >> n >> m;
    edge.resize(m);
    out.resize(m);
    memo.resize(m+1,vector<vector<int>>(n*2,vector<int>(n*2,-1)));
    place.resize(m+1,vector<vector<int>>(n*2,vector<int>(n*2,-1)));
    for (int i = 0; i < m; i++)
    {
        int a,b; cin >> a >> b; a--; b--;
        if(b<a) b+=n;
        edge[i]={{a,b},i};
    }
    sort(all(edge));
    l=edge[0].first.first;
    int r=edge[0].first.second;
    for (int i = 1; i < m; i++)
    {
        if(edge[i-1].first.first-1<=r) r=max(edge[i-1].first.second,r);
        l2=edge[i].first.first;
        if(dp(i+1,r,edge[i].first.second)){
            for (int j = 0; j < i; j++) out[edge[j].second]=0;
            out[edge[i].second]=1;
            prnt(i+1,r,edge[i].first.second);
            for (int j = 0; j < m; j++) cout << out[j];
            cout << "\n";
            return 0;
        }
        for (int j = 0; j <= m; j++)
        {
            for (int k = 0; k < 2*n; k++)
            {
                for (int _l = 0; _l < 2*n; _l++)
                {
                    memo[j][k][_l]=-1;
                    place[j][k][_l]=-1;
                }
            }
        }
    }
    cout << "impossible\n";
    return 0;
}

• Subtask 1: 13 / 13
• Subtask 2: 0 / 20
• Subtask 3: 0 / 22
• Subtask 4: 0 / 19
• Subtask 5: 0 / 26