This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define fi first
#define se second
typedef long double ld;
const ll inf = 1e9;
const ld eps = 1e-8;
const ll logs = 32;
#include <cmath>
bool ch = 0;
vector<vector<pair<ll, ll>>> g;
vector<bool> ok;
vector<ll> col;
void dfs(ll v, ll c = 0) {
col[v] = c;
for (auto [u, ind] : g[v]) {
if (!ok[ind]) {
continue;
}
if (col[u] == -1)
dfs(u, 1 - c);
else if (col[u] == col[v])
ch = 1;
}
}
struct dsu {
vector<ll> par, dist, sz;
void init(ll n) {
par.resize(n);
dist.resize(n);
sz.resize(n);
for (ll i = 0; i < n; i++) {
par[i] = i;
sz[i] = 1;
}
}
ll get_par(ll v) {
if (v == par[v])
return v;
ll ans = get_par(par[v]);
dist[v] = (dist[par[v]] + dist[v]) % 2;
par[v] = ans;
return ans;
}
ll get_dist(ll v) {
if (v == par[v])
return 0;
return (dist[v] + get_dist(par[v])) % 2;
}
void union_(ll v, ll u) {
ll nv = get_par(v);
ll nu = get_par(u);
if (nv == nu) {
if (get_dist(v) == get_dist(u))
ch = 1;
return;
}
if (sz[nu] > sz[nv]) {
swap(nv, nu);
swap(u, v);
}
ll uu = get_dist(u), vv = get_dist(v);
dist[nu] = (get_dist(u) + get_dist(v) + 1) % 2;
par[nu] = nv;
sz[nv] += sz[nu];
}
};
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
ll n, m, q;
cin >> n >> m >> q;
if (n <= 2000 && m <= 2000 && q <= 2000) {
g.resize(n);
ok.resize(m, 1);
col.resize(n);
for (ll i = 0; i < m; i++) {
ll v, u;
cin >> v >> u;
g[v - 1].push_back({u - 1, i});
g[u - 1].push_back({v - 1, i});
}
for (ll qw = 0; qw < q; qw++) {
ll l, r;
cin >> l >> r;
for (ll i = 0; i < m; i++) {
if (l - 1 <= i && i < r)
ok[i] = 0;
else
ok[i] = 1;
}
for (ll i = 0; i < n; i++) {
col[i] = -1;
}
bool check = 0;
for (ll i = 0; i < n; i++) {
if (col[i] == -1) {
ch = 0;
dfs(i);
if (ch)
check = 1;
}
}
if (check) {
cout << "YES" << '\n';
} else {
cout << "NO" << '\n';
}
}
} else {
vector<pair<ll, ll>> vert(m);
for (ll i = 0; i < m; i++) {
ll v, u;
cin >> v >> u;
vert[i] = {v - 1, u - 1};
}
reverse(vert.begin(), vert.end());
ll val = -1;
dsu dsu;
dsu.init(n);
for (ll i = 0; i < m; i++) {
auto [v, u] = vert[i];
ch = 0;
dsu.union_(v, u);
if (ch) {
val = (m - i);
break;
}
}
//cout << val << endl;
for (ll qw = 0; qw < q; qw++) {
ll l, r;
cin >> l >> r;
if (r < val)
cout << "YES" << '\n';
else
cout << "NO" << '\n';
}
}
}
Compilation message (stderr)
Joker.cpp: In member function 'void dsu::union_(ll, ll)':
Joker.cpp:66:12: warning: unused variable 'uu' [-Wunused-variable]
66 | ll uu = get_dist(u), vv = get_dist(v);
| ^~
Joker.cpp:66:30: warning: unused variable 'vv' [-Wunused-variable]
66 | ll uu = get_dist(u), vv = get_dist(v);
| ^~
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