CF1039C.Network Safety

---

目录

• [TOC]

题目链接

CF1039C.Network Safety

题解

对于一对相邻点，^异或后相同的值唯一a_i ^ t= b_i,a_i ^ b_i = t
对于不在t集合的直接算上
对于t集合,对于每个t分别计算联块的个数,然后加上联通块子集个数

代码

#include<map> 
#include<vector> 
#include<cstdio> 
#include<algorithm> 
#define int long long
#define gc getchar()
#define pc putchar 
inline int read() { 
	int x = 0,f = 1; 
	char c = gc; 
	while(c < '0' || c > '9')c = gc; 
	while(c <= '9' && c >= '0') x = x * 10 + c - '0',c = gc; 
	return x * f; 
}
void print(int x) { 
	if(x < 0) { 
		pc('-'); 
		x = -x; 
	} 
	if(x >= 10) print(x / 10); 
	pc(x % 10 + '0'); 
} 
const int maxn = 1000007; 
const int mod = 1e9 + 7; 
#define LL long long
int n,m,k; 
int a[maxn]; 
int p[maxn]; 
std::vector<int>v[maxn]; 
int id[maxn]; 
int bel[maxn]; 
int fa[maxn]; 
int find(int x) { 
	if(fa[x] != x) fa[x] = find(fa[x]); 
	return fa[x]; 
} 
struct node { 
	int u,v; 
} e[maxn << 1]; 
std::map<LL,int>mp; 
main() { 
	int tot = 0; 
	n = read(), m = read() , k = read(); 
	p[0] = 1; 
	for(int i = 1;i <= n;++ i) p[i] = p[i - 1] * 2 % mod; 
	for(int i = 1;i <= n;++ i) a[i] = read(),fa[i] = i; 
	for(int i = 1;i <= m;++ i) { 
		e[i].u = read(),e[i].v = read(); 
		int t = a[e[i].u] ^ a[e[i].v]; 
		if(!mp[t]) mp[t] = ++ tot; 
		id[++ tot] = t; 
		v[mp[t]].push_back(i);  
	} 
    int ans = 1ll * ((1ll << k) - tot) % mod * p[n] % mod; 
	for(int i = 1;i <= tot;++ i) { 
		int size = n; 
		for(int j = 0;j < v[i].size();++ j) { 
			int E = v[i][j]; 
			int fx = find(e[E].u),fy = find(e[E].v); 
			if(fx != fy) { 
				fa[fx] = fy; 
				size --; 
			} 
		} 
		(ans += p[size]) %= mod; 
		for(int j = 0;j < v[i].size();++ j) { 
			int E = v[i][j]; 
			fa[e[E].u] = e[E].u; 
			fa[e[E].v] = e[E].v; 
		} 
	} 
	print(ans); 
	pc('
'); 
	return 0; 
}