Submission #1084900

#	Time	Username	Problem	Language	Result	Execution time	Memory
1084900		Sunbae	Synchronization (JOI13_synchronization)	C++17	100 / 100	213 ms	23388 KiB

synchronization

#include <bits/stdc++.h>
#define mp make_pair
#define F first
#define S second
using namespace std;
using pii = pair<int,int>;
const int N = 1e5 + 5;
vector<int> g[N];
pii e[N], A[N];
int timer, tin[N], tout[N], up[N][17], bit[N<<1], LOG;
bool active[N];
void upd(int i, int val){ for(; i<(N<<1); i+=i&-i) bit[i] += val;}
int qry(int i){ int res = 0; for(; i; i-=i&-i) res += bit[i]; return res;}
void dfs(int u, int p){
	up[u][0] = p; tin[u] = timer++;
	for(int j = 1; j<LOG; ++j) up[u][j] = up[up[u][j-1]][j-1];
	for(int v : g[u]) if(v != p) dfs(v, u);
	tout[u] = timer++;	
}

int find_root(int u){
	int v = u, qry_u = qry(tin[u]);
	for(int j = LOG-1; j>=0; --j) if(qry(tin[up[v][j]]) == qry_u) v = up[v][j];
	return v;
}

signed main(){
	int n, m, q; scanf("%d %d %d", &n, &m, &q); LOG = 32 - __builtin_clz(n);
	for(int i = 0, u, v; i<n-1; ++i){
		scanf("%d %d", &u, &v); --u; --v;
		g[u].push_back(v); g[v].push_back(u);
		e[i] = mp(u, v);
	}
	timer = 1; dfs(0, 0);
	for(int i= 0; i<n-1; ++i){
		int u = e[i].F, v = e[i].S; if(tin[u] > tin[v]) swap(u, v);
		upd(tin[v], +1); upd(tout[v], -1);
	}
	fill(A, A+n, mp(1, 0));
	for(int i = 0; i<m; ++i){
		int j; scanf("%d", &j); --j;
		int u = e[j].F, v = e[j].S; if(tin[u] > tin[v]) swap(u, v);
		if(active[j]){ //remove
			A[v] = mp(A[find_root(u)].F, A[find_root(u)].F);
			upd(tin[v], +1); upd(tout[v], -1);
		}else{ //add
			A[find_root(u)].F += A[v].F - A[v].S;
			upd(tin[v], -1); upd(tout[v], +1);
		}
		active[j] ^= 1;
	}
	for(int u; q--; ) scanf("%d", &u), printf("%d\n", A[find_root(--u)].F);
}

Compilation message (stderr)

synchronization.cpp: In function 'int main()':
synchronization.cpp:28:20: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   28 |  int n, m, q; scanf("%d %d %d", &n, &m, &q); LOG = 32 - __builtin_clz(n);
      |               ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
synchronization.cpp:30:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |   scanf("%d %d", &u, &v); --u; --v;
      |   ~~~~~^~~~~~~~~~~~~~~~~
synchronization.cpp:41:15: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   41 |   int j; scanf("%d", &j); --j;
      |          ~~~~~^~~~~~~~~~
synchronization.cpp:52:25: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   52 |  for(int u; q--; ) scanf("%d", &u), printf("%d\n", A[find_root(--u)].F);
      |                    ~~~~~^~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 10 / 10
• Subtask 4: 20 / 20
• Subtask 5: 40 / 40