Submission #446931

#	Time	Username	Problem	Language	Result	Execution time	Memory
446931		JovanB	Joker (BOI20_joker)	C++17	100 / 100	381 ms	12560 KiB

Joker

#include <bits/stdc++.h>
using namespace std;
 
using ll = long long;
using ld = long double;
 
const int MAXN = 200000;
 
int ea[MAXN+5];
int eb[MAXN+5];
 
struct DSU{
    int n;
    int par[MAXN+5];
    bool col[MAXN+5];
    int rnk[MAXN+5];
    struct operacija{
        int a, b, rnka, rnkb;
    };
    stack <operacija> ops;
    void init(){
        for(int i=1; i<=n; i++){
            par[i] = i;
        }
    }
    int root(int x){
        return x == par[x] ? x : root(par[x]);
    }
    int color(int x){
        if(x == par[x]) return 0;
        if(col[x]) return 1^color(par[x]);
        return color(par[x]);
    }
    bool add(int a, int b){
        int a1 = root(a);
        int b1 = root(b);
        if(a1 == b1){
            ops.push({0, 0, 0, 0});
            return color(a) != color(b);
        }
        if(rnk[a1] < rnk[b1]) swap(a1, b1);
        ops.push({a1, b1, rnk[a1], rnk[b1]});
        if(rnk[a1] == rnk[b1]) rnk[a1]++;
        if(color(a) == color(b)) col[b1] = 1;
        par[b1] = a1;
        return 1;
    }
    void brisi(){
        operacija op = ops.top();
        ops.pop();
        int a = op.a;
        int b = op.b;
        rnk[a] = op.rnka;
        rnk[b] = op.rnkb;
        par[a] = a;
        par[b] = b;
        col[a] = col[b] = 0;
    }
} dsu;
 
int sol[MAXN+5];
 
void resi(int l, int r, int tl, int tr){
    if(l > r) return;
    int mid = (l+r)/2;
    bool moze = 1;
    for(int i=r; i>mid; i--){
        dsu.add(ea[i], eb[i]);
    }
    int brd;
    for(brd = tl; brd<mid; brd++){
        if(!dsu.add(ea[brd], eb[brd])){
            dsu.brisi();
            break;
        }
    }
    sol[mid] = brd;
    for(int i=brd-1; i>=tl; i--) dsu.brisi();
    dsu.add(ea[mid], eb[mid]);
    resi(l, mid-1, tl, sol[mid]);
    dsu.brisi();
    for(int i=r; i>mid; i--) dsu.brisi();
    for(int i=brd-1; i>=tl; i--){
        dsu.add(ea[i], eb[i]);
    }
    resi(mid+1, r, sol[mid], tr);
    for(int i=brd-1; i>=tl; i--) dsu.brisi();
}
 
int main(){
    ios_base::sync_with_stdio(false), cin.tie(0);
    cout.precision(10);
    cout << fixed;
 
    int n, m, q;
    cin >> n >> m >> q;
    for(int i=1; i<=m; i++){
        cin >> ea[i] >> eb[i];
    }
    dsu.n = n;
    dsu.init();
    int bord = m;
    for(int i=m-1; i>=1; i--){
        if(!dsu.add(ea[i+1], eb[i+1])){
            bord = i+1;
            break;
        }
        if(i == 1) bord = 1;
    }
    for(int i=max(2, bord); i<=m; i++) dsu.brisi();
    resi(bord, m, 1, m);
    for(int i=1; i<=q; i++){
        int x, y;
        cin >> x >> y;
        if(sol[y] >= x) cout << "NO\n";
        else cout << "YES\n";
    }
    return 0;
}

Compilation message (stderr)

Joker.cpp: In function 'void resi(int, int, int, int)':
Joker.cpp:66:10: warning: unused variable 'moze' [-Wunused-variable]
   66 |     bool moze = 1;
      |          ^~~~

• Subtask 1: 6 / 6
• Subtask 2: 8 / 8
• Subtask 3: 25 / 25
• Subtask 4: 10 / 10
• Subtask 5: 22 / 22
• Subtask 6: 29 / 29