Submission #43358

#	Time	Username	Problem	Language	Result	Execution time	Memory
43358		szawinis	Synchronization (JOI13_synchronization)	C++14	100 / 100	279 ms	20348 KiB

synchronization

#include <bits/stdc++.h>
#define rep(i, a, b) for(int i = a; i < b; i++)
#define repi(i, a, b) for(int i = a; i <= b; i++)
#define drep(i, a, b) for(int i = a; i >= b; i--)
using namespace std;
const int N = 1 << 18;

int n, m, q, u[N], v[N], d[N], s[N], e[N], ord[N], res[N], last[N];
bool state[N];
vector<int> g[N];
void dfs(int u, int p) {
	static int idx = 0;
	s[u] = ++idx;
	ord[s[u]] = u;
	for(int v: g[u]) if(v != p) d[v] = d[u] + 1, dfs(v, u);
	e[u] = idx;
}
int t[2*N];
void build(int i = 1, int l = 0, int r = N-1) {
	if(l == r) {
		t[i] = e[ord[l]];
		return;
	}
	int mid = l+r >> 1;
	build(i<<1, l, mid);
	build(i<<1|1, mid+1, r);
	t[i] = max(t[i<<1], t[i<<1|1]);
}
void update(int targ, int val, int i = 1, int l = 0, int r = N-1) {
	if(l == r) {
		t[i] = val;
		return;
	}
	int mid = l+r >> 1;
	if(targ <= mid) update(targ, val, i<<1, l, mid);
	else update(targ, val, i<<1|1, mid+1, r);
	t[i] = max(t[i<<1], t[i<<1|1]);
}
int get_root(int tl, int tr, int i = 1, int l = 0, int r = N-1) {
	if(l > tl || t[i] < tr) return -1;
	if(l == r) return ord[l];
	int mid = l+r >> 1, ret = get_root(tl, tr, i<<1|1, mid+1, r);
	if(ret != -1) return ret;
	return get_root(tl, tr, i<<1, l, mid);
}
int main() {
	scanf("%d %d %d", &n, &m, &q);
	rep(i, 1, n) {
		scanf("%d %d", u+i, v+i);
		g[u[i]].push_back(v[i]);
		g[v[i]].push_back(u[i]);
	}
	dfs(1, 0);
	build();
	fill(res+1, res+n+1, 1);
	rep(zz, 0, m) {
		int i; scanf("%d", &i);
		if(d[u[i]] > d[v[i]]) swap(u[i], v[i]);
		int root = get_root(s[u[i]], e[u[i]]);
		if(!state[i]) {
			res[root] += res[v[i]] - last[v[i]];
			update(s[v[i]], -1); // no longer a candidate for being root of tree in forest
		} else {
			res[v[i]] = res[root];
			last[v[i]] = res[root];
			update(s[v[i]], e[v[i]]); // candidacy of being root restored
		}
		state[i] ^= 1;
	}
	rep(zz, 0, q) {
		int vert; scanf("%d", &vert);
		printf("%d\n", res[get_root(s[vert], e[vert])]);
	}
}

Compilation message (stderr)

synchronization.cpp: In function 'void build(int, int, int)':
synchronization.cpp:24:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid = l+r >> 1;
             ^
synchronization.cpp: In function 'void update(int, int, int, int, int)':
synchronization.cpp:34:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid = l+r >> 1;
             ^
synchronization.cpp: In function 'int get_root(int, int, int, int, int)':
synchronization.cpp:42:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid = l+r >> 1, ret = get_root(tl, tr, i<<1|1, mid+1, r);
             ^
synchronization.cpp: In function 'int main()':
synchronization.cpp:47:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d %d", &n, &m, &q);
                               ^
synchronization.cpp:49:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", u+i, v+i);
                           ^
synchronization.cpp:57:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   int i; scanf("%d", &i);
                         ^
synchronization.cpp:71:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   int vert; scanf("%d", &vert);
                               ^

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