BZOJ 1123:城市道路

Sol

就是求割点，把贡献算一下就好。。。直接tarjan

# include <bits/stdc++.h>
# define RG register
# define IL inline
# define Fill(a, b) memset(a, b, sizeof(a))
using namespace std;
typedef long long ll;
const int _(1e5 + 10);

IL ll Read(){
	RG ll x = 0, z = 1; RG char c = getchar();
	for(; c < '0' || c > '9'; c = getchar()) z = c == '-' ? -1 : 1;
	for(; c >= '0' && c <= '9'; c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
	return x * z;
}

int n, fst[_], nxt[_ << 2], to[_ << 2], cnt, m, dfn[_], size[_], Index, low[_];
ll ans[_];

IL void Add(RG int u, RG int v){  to[cnt] = v; nxt[cnt] = fst[u]; fst[u] = cnt++;  }

IL void Dfs(RG int u, RG int ff){
	dfn[u] = low[u] = ++Index; size[u] = 1; RG int sum = 0;
	for(RG int e = fst[u]; e != -1; e = nxt[e]){
		if(to[e] == ff) continue;
		if(!dfn[to[e]]){
			Dfs(to[e], u);
			size[u] += size[to[e]];
			low[u] = min(low[u], low[to[e]]);
			if(low[to[e]] >= dfn[u]) ans[u] += 1LL * sum * size[to[e]] * 2, sum += size[to[e]];
		}
		else low[u] = min(low[u], dfn[to[e]]);
	}
	ans[u] += 1LL * sum * (n - sum - 1) * 2;
}

int main(RG int argc, RG char* argv[]){
    n = Read(); m = Read();
	for(RG int i = 1; i <= n; ++i) ans[i] = n + n - 2, fst[i] = -1;
    for(RG int i = 1, u, v; i <= m; ++i) u = Read(), v = Read(), Add(u, v), Add(v, u);
	Dfs(1, 0);
	for(RG int i = 1; i <= n; ++i) printf("%lld\n", ans[i]);
    return 0;
}