Submission #766166

#	Time	Username	Problem	Language	Result	Execution time	Memory
766166		keta_tsimakuridze	Joker (BOI20_joker)	C++14	100 / 100	500 ms	20996 KiB

Joker

#include<bits/stdc++.h>
#define f first
#define s second
#define int long long
#define pii pair<int,int>
using namespace std;
const int N = 2e5 + 5, mod = 1e9 + 7; // !
int t, p[N], up[N], sz[N], ans[N], odd = 0;
vector<int> V[N];
pair<int,int> e[N];
stack<int> st;
pair<int,int> find(int u) {
    if(p[u] == u) return {u, 0};
    pii P = find(p[u]);
    P.s ^= up[u];
    return P;
}
void merge(int u, int v) {
    pii U = find(u), V = find(v);
    if(sz[U.f] < sz[V.f]) swap(U, V);
    if(U.f != V.f) {
        st.push(V.f);
        p[V.f] = U.f;
        sz[U.f] += sz[V.f];
        up[V.f] = (U.s != V.s ? 0 : 1);
        return;
    }
    if(U.s == V.s) ++odd, st.push(-1);
}
void rollback(int X) {
    while(st.size() > X) {
        int x = st.top();
        st.pop();
        if(x == -1) --odd;
        else sz[p[x]] -= sz[x], p[x] = x, up[x] = 0;
    }
}
void solve(int l, int r, int L, int R) {
    int mid = (l + r) / 2;
    int I = st.size();
    for(int i = l; i <= mid; i++) {
        merge(e[i].f, e[i].s);
    }
    int I2 = st.size();
    int opt = R;
    while(opt && !odd) {
        --opt;
        if(!opt) break;
        merge(e[opt].f, e[opt].s);

    }
    ans[mid] = opt;
    rollback(I2);
    if(mid + 1 <= r) solve(mid + 1, r, opt, R);

    rollback(I);
    for(int i = max(1ll, opt); i < R; i++) merge(e[i].f, e[i].s);
    if(l < mid) solve(l, mid - 1, L, opt);
    rollback(I);

}
main(){
    int n, m, q;
    cin >> n >> m >> q;
    for(int i = 1; i <= n; i++) p[i] = i, sz[i] = 1;

    for(int i = 1; i <= m; i++) cin >> e[i].f >> e[i].s;

    e[0] = {0, 1};
    solve(0, m, 0, m + 1);
//    for(int i = 1; i <= m; i++) cout << ans[i] << " "; cout << endl;
    for(int i = 1; i <= q; i++) {
        int l, r;
        cin >> l >> r;
        cout << (ans[l - 1] > r ? "YES\n" : "NO\n");
    }
 }

Compilation message (stderr)

Joker.cpp: In function 'void rollback(long long int)':
Joker.cpp:31:21: warning: comparison of integer expressions of different signedness: 'std::stack<long long int>::size_type' {aka 'long unsigned int'} and 'long long int' [-Wsign-compare]
   31 |     while(st.size() > X) {
      |           ~~~~~~~~~~^~~
Joker.cpp: At global scope:
Joker.cpp:62:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   62 | main(){
      | ^~~~

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