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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. typedef long long ll;
  5. typedef long double ld;
  6. typedef double db; 
  7. typedef string str; 
  8.  
  9. typedef pair<int,int> pi;
  10. typedef pair<ll,ll> pl; 
  11. typedef pair<db,db> pd; 
  12.  
  13. typedef vector<int> vi; 
  14. typedef vector<ll> vl; 
  15. typedef vector<db> vd; 
  16. typedef vector<str> vs; 
  17. typedef vector<pi> vpi;
  18. typedef vector<pl> vpl; 
  19. typedef vector<pd> vpd; 
  20.  
  21. #define mp make_pair
  22. #define f first
  23. #define s second
  24. #define sz(x) (int)(x).size()
  25. #define all(x) begin(x), end(x)
  26. #define rall(x) (x).rbegin(), (x).rend() 
  27. #define rsz resize
  28. #define ins insert 
  29. #define ft front() 
  30. #define bk back()
  31. #define pf push_front 
  32. #define pb push_back
  33. #define eb emplace_back 
  34. #define lb lower_bound 
  35. #define ub upper_bound 
  36.  
  37. #define FOR(i,a,b) for (int i = (a); i < (b); ++i)
  38. #define F0R(i,a) FOR(i,0,a)
  39. #define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
  40. #define R0F(i,a) ROF(i,0,a)
  41. #define trav(a,x) for (auto& a: x)
  42.  
  43. const int MOD = 1e9+7; // 998244353;
  44. const int MX = 2e5+5; 
  45. const ll INF = 1e18; 
  46. const ld PI = acos((ld)-1);
  47. const int xd[4] = {1,0,-1,0}, yd[4] = {0,1,0,-1}; 
  48. mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count()); 
  49.  
  50. template<class T> bool ckmin(T& a, const T& b) { 
  51. 	return b < a ? a = b, 1 : 0; }
  52. template<class T> bool ckmax(T& a, const T& b) { 
  53. 	return a < b ? a = b, 1 : 0; } 
  54. constexpr int pct(int x) { return __builtin_popcount(x); } 
  55. constexpr int bits(int x) { return 31-__builtin_clz(x); } // floor(log2(x)) 
  56. ll cdiv(ll a, ll b) { return a/b+((a^b)>0&&a%b); } // divide a by b rounded up
  57. ll fdiv(ll a, ll b) { return a/b-((a^b)<0&&a%b); } // divide a by b rounded down
  58. ll half(ll x) { return fdiv(x,2); }
  59.  
  60. template<class T, class U> T fstTrue(T lo, T hi, U f) {
  61. 	hi ++; assert(lo <= hi); // assuming f is increasing
  62. 	while (lo < hi) { // find first index such that f is true 
  63. 		T mid = half(lo+hi);
  64. 		f(mid) ? hi = mid : lo = mid+1; 
  65. 	} 
  66. 	return lo;
  67. }
  68. template<class T, class U> T lstTrue(T lo, T hi, U f) {
  69. 	lo --; assert(lo <= hi); // assuming f is decreasing
  70. 	while (lo < hi) { // find first index such that f is true 
  71. 		T mid = half(lo+hi+1);
  72. 		f(mid) ? lo = mid : hi = mid-1;
  73. 	} 
  74. 	return lo;
  75. }
  76. template<class T> void remDup(vector<T>& v) { 
  77. 	sort(all(v)); v.erase(unique(all(v)),end(v)); }
  78.  
  79. // INPUT
  80. template<class A> void re(complex<A>& c);
  81. template<class A, class B> void re(pair<A,B>& p);
  82. template<class A> void re(vector<A>& v);
  83. template<class A, size_t SZ> void re(array<A,SZ>& a);
  84.  
  85. template<class T> void re(T& x) { cin >> x; }
  86. void re(db& d) { str t; re(t); d = stod(t); }
  87. void re(ld& d) { str t; re(t); d = stold(t); }
  88. template<class H, class... T> void re(H& h, T&... t) { re(h); re(t...); }
  89.  
  90. template<class A> void re(complex<A>& c) { A a,b; re(a,b); c = {a,b}; }
  91. template<class A, class B> void re(pair<A,B>& p) { re(p.f,p.s); }
  92. template<class A> void re(vector<A>& x) { trav(a,x) re(a); }
  93. template<class A, size_t SZ> void re(array<A,SZ>& x) { trav(a,x) re(a); }
  94.  
  95. // TO_STRING
  96. #define ts to_string
  97. str ts(char c) { return str(1,c); }
  98. str ts(const char* s) { return (str)s; }
  99. str ts(str s) { return s; }
  100. str ts(bool b) { 
  101. 	#ifdef LOCAL
  102. 		return b ? "true" : "false"; 
  103. 	#else 
  104. 		return ts((int)b);
  105. 	#endif
  106. }
  107. template<class A> str ts(complex<A> c) { 
  108. 	stringstream ss; ss << c; return ss.str(); }
  109. str ts(vector<bool> v) {
  110. 	str res = "{"; F0R(i,sz(v)) res += char('0'+v[i]);
  111. 	res += "}"; return res; }
  112. template<size_t SZ> str ts(bitset<SZ> b) {
  113. 	str res = ""; F0R(i,SZ) res += char('0'+b[i]);
  114. 	return res; }
  115. template<class A, class B> str ts(pair<A,B> p);
  116. template<class T> str ts(T v) { // containers with begin(), end()
  117. 	#ifdef LOCAL
  118. 		bool fst = 1; str res = "{";
  119. 		for (const auto& x: v) {
  120. 			if (!fst) res += ", ";
  121. 			fst = 0; res += ts(x);
  122. 		}
  123. 		res += "}"; return res;
  124. 	#else
  125. 		bool fst = 1; str res = "";
  126. 		for (const auto& x: v) {
  127. 			if (!fst) res += " ";
  128. 			fst = 0; res += ts(x);
  129. 		}
  130. 		return res;
  131.  
  132. 	#endif
  133. }
  134. template<class A, class B> str ts(pair<A,B> p) {
  135. 	#ifdef LOCAL
  136. 		return "("+ts(p.f)+", "+ts(p.s)+")"; 
  137. 	#else
  138. 		return ts(p.f)+" "+ts(p.s);
  139. 	#endif
  140. }
  141.  
  142. // OUTPUT
  143. template<class A> void pr(A x) { cout << ts(x); }
  144. template<class H, class... T> void pr(const H& h, const T&... t) { 
  145. 	pr(h); pr(t...); }
  146. void ps() { pr("\n"); } // print w/ spaces
  147. template<class H, class... T> void ps(const H& h, const T&... t) { 
  148. 	pr(h); if (sizeof...(t)) pr(" "); ps(t...); }
  149.  
  150. // DEBUG
  151. void DBG() { cerr << "]" << endl; }
  152. template<class H, class... T> void DBG(H h, T... t) {
  153. 	cerr << ts(h); if (sizeof...(t)) cerr << ", ";
  154. 	DBG(t...); }
  155. #ifdef LOCAL // compile with -DLOCAL
  156. 	#define dbg(...) cerr << "LINE(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
  157. #else
  158. 	#define dbg(...) 0
  159. #endif
  160.  
  161. // FILE I/O
  162. void setIn(str s) { freopen(s.c_str(),"r",stdin); }
  163. void setOut(str s) { freopen(s.c_str(),"w",stdout); }
  164. void unsyncIO() { ios_base::sync_with_stdio(0); cin.tie(0); }
  165. void setIO(str s = "") {
  166. 	unsyncIO();
  167. 	// cin.exceptions(cin.failbit); 
  168. 	// throws exception when do smth illegal
  169. 	// ex. try to read letter into int
  170. 	if (sz(s)) { setIn(s+".in"), setOut(s+".out"); } // for USACO
  171. }
  172.  
  173. /**
  174.  * Description: Disjoint Set Union with Rollback
  175.  * Source: see DSU
  176.  * Verification: *
  177.  */
  178.  
  179. struct DSUrb {
  180. 	vi e, off; void init(int n) { e = vi(n,-1); off = vi(n); }
  181. 	pi get(int x) {
  182. 		int OFF = 0;
  183. 		while (e[x] >= 0) {
  184. 			OFF ^= off[x];
  185. 			x = e[x];
  186. 		}
  187. 		return {x,OFF};
  188. 	}
  189. 	vector<array<int,4>> mod;
  190. 	int unite(int _x, int _y) { // union by size
  191. 		pi x = get(_x), y = get(_y);
  192. 		if (x.f == y.f) {
  193. 			if (x.s == y.s) return 0;
  194. 			mod.pb({-1,-1,-1,-1});
  195. 			return 1;
  196. 		}
  197. 		if (e[x.f] > e[y.f]) swap(x,y);
  198. 		mod.pb({x.f,y.f,e[x.f],e[y.f]});
  199. 		e[x.f] += e[y.f]; e[y.f] = x.f; off[y.f] = x.s^y.s^1;
  200. 		return 1;
  201. 	}
  202. 	void rollback() {
  203. 		auto a = mod.bk; mod.pop_back();
  204. 		if (a[0] != -1) e[a[0]] = a[2], e[a[1]] = a[3];
  205. 	}
  206. };
  207.  
  208. DSUrb D;
  209. int N,M,Q;
  210. int fst[MX],u[MX],v[MX];
  211.  
  212. bool ad(int ind) { 
  213. 	dbg("AD",ind);
  214. 	if (ind == M+1) return 1;
  215. 	return D.unite(u[ind],v[ind]); 
  216. }
  217. void restore(int _sz) { 
  218. 	while (sz(D.mod) > _sz) {
  219. 		D.rollback(); 
  220. 		dbg("ROLLBACK");
  221. 	}
  222. }
  223.  
  224. void divi(int xl, int xr, int yl, int yr) { 
  225. 	// removing xr ... yr is bipartite, move ? left while possible
  226. 	if (xl > xr) return;
  227. 	dbg("DIVI",xl,xr,yl,yr,sz(D.mod));
  228. 	assert(yl <= yr);
  229. 	int xm = (xl+xr)/2;
  230. 	int res = -1;
  231. 	int _sz = sz(D.mod);
  232. 	FOR(i,xl,xm) if (!ad(i)) { 
  233. 		res = yr; assert(res == M+1);
  234. 		break;
  235. 	}
  236. 	int _sz2 = sz(D.mod);
  237. 	if (res == -1) {
  238. 		int i = yr; while (i > yl && ad(i)) i --;
  239. 		res = i;
  240. 	}
  241. 	fst[xm] = res;
  242. 	dbg("SET",xm,fst[xm]);
  243. 	if (fst[xm] == M+1) {
  244. 		FOR(i,xm+1,xr+1) fst[i] = M+1;
  245. 	} else {
  246. 		restore(_sz2);
  247. 		if (!ad(xm)) {
  248. 			FOR(i,xm+1,xr+1) fst[i] = M+1;
  249. 		} else {
  250. 			divi(xm+1,xr,fst[xm],yr);
  251. 		}
  252. 	}
  253. 	restore(_sz);
  254. 	FOR(i,fst[xm]+1,yr+1) assert(ad(i));
  255. 	divi(xl,xm-1,yl,fst[xm]); // add those from fst[xm] to r-1
  256. 	restore(_sz);
  257. }
  258.  
  259. int main() {
  260. 	setIO(); re(N,M,Q); D.init(N+1);
  261. 	FOR(i,1,M+1) re(u[i],v[i]);
  262. 	divi(1,M,1,M+1);
  263. 	FOR(i,1,M+1) dbg(i,fst[i]);
  264. 	// FOR(i,1,M+1) { // M^2 * DSU solution
  265. 	// 	DSUrb D; D.init(N+1);
  266. 	// 	FOR(j,1,i) {
  267. 	// 		if (!D.unite(u[j],v[j])) {
  268. 	// 			fst[i] = M+1;
  269. 	// 			break;
  270. 	// 		}
  271. 	// 		dbg("UNITED",u[j],v[j]);
  272. 	// 	}
  273. 	// 	if (fst[i] == M+1) continue;
  274. 	// 	int j = M; 
  275. 	// 	while (j >= i) {
  276. 	// 		if (D.unite(u[j],v[j])) j --;
  277. 	// 		else {
  278. 	// 			dbg("NOPE",u[j],v[j]);
  279. 	// 			break;
  280. 	// 		}
  281. 	// 	}
  282. 	// 	fst[i] = j;
  283. 	// 	dbg(i,fst[i]);
  284. 	// }
  285. 	F0R(i,Q) {
  286. 		int l,r; re(l,r);
  287. 		if (r >= fst[l]) ps("NO");
  288. 		else ps("YES");
  289. 	}
  290. 	// you should actually read the stuff at the bottom
  291. }
  292.  
  293. /* stuff you should look for
  294. 	* int overflow, array bounds
  295. 	* special cases (n=1?)
  296. 	* do smth instead of nothing and stay organized
  297. 	* WRITE STUFF DOWN
  298. */
  299.  
  300.  
Success #stdin #stdout 0s 4312KB
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https://ideone.com/EBWCgV
BOI 2020 C (D&C)
language:
C++14 (gcc 8.3)
created:
3 years ago
visibility:
secret

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