#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
//#include "Lgrader.cpp"
using namespace std;
using namespace __gnu_pbds;
template<class T, class T2> inline int chkmax(T &x, const T2 &y) { return x < y ? x = y, 1 : 0; }
template<class T, class T2> inline int chkmin(T &x, const T2 &y) { return x > y ? x = y, 1 : 0; }
const int MAXN = (1 << 20);
const int mod = (int)1e9;
struct chash { int operator()(pair<int, int> x) const { return x.first * 42 + x.second; } };
int answer;
map<pair<int, int>, int> S;
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, -1, 1};
int cnt1[MAXN], cnt2[MAXN];
vector<int> adj[MAXN];
int par[MAXN], sz[MAXN];
int root(int u) { return u == par[u] ? u : par[u] = root(par[u]); }
int root(pair<int, int> x) { return root(S[x]); }
void unite(pair<int, int> a, pair<int, int> b)
{
int u = root(S[a]), v = root(S[b]);
if(u == v) return;
if(sz[u] > sz[v])
swap(u, v);
sz[v] += sz[u];
par[u] = v;
}
int dp[MAXN];
void pre_dfs(int u, int pr)
{
dp[u] = sz[u];
for(int v: adj[u])
if(v != pr)
{
pre_dfs(v, u);
dp[u] = (dp[u] + dp[v]) % mod;
}
}
int n;
void dfs(int u, int pr)
{
if(u != pr)
{
int curr = 0;
curr = (dp[u] * 1ll * (n - dp[u])) % mod;
answer = (answer + curr) % mod;
}
for(int v: adj[u])
if(v != pr)
dfs(v, u);
}
int DistanceSum(int N, int *X, int *Y)
{
::n = N;
answer = 0;
vector<pair<int, int> > li;
for(int i = 0; i < N; i++)
li.push_back({X[i], Y[i]});
int r, idx = 0;
for(auto it: li)
S[it] = ++idx;
for(int i = 1; i <= idx; i++) adj[i].clear();
for(int i = 1; i <= idx; i++)
par[i] = i, sz[i] = 1;
for(auto it: li)
for(int d = 0; d < 2; d++)
{
pair<int, int> nxt = {dx[d] + it.first, dy[d] + it.second};
if(S.find(nxt) != S.end())
unite(nxt, it);
}
for(auto it: li)
for(int d = 2; d < 4; d++)
{
pair<int, int> nxt = {dx[d] + it.first, dy[d] + it.second};
if(S.find(nxt) != S.end())
adj[root(nxt)].push_back(root(S[it]));
}
for(int i = 1; i <= n; i++)
{
sort(adj[i].begin(), adj[i].end());
adj[i].erase(unique(adj[i].begin(), adj[i].end()), adj[i].end());
}
r = root(1);
pre_dfs(r, r);
dfs(r, r);
for(int i = 1; i <= idx; i++) adj[i].clear();
for(int i = 1; i <= idx; i++)
par[i] = i, sz[i] = 1;
for(auto it: li)
for(int d = 2; d < 4; d++)
{
pair<int, int> nxt = {dx[d] + it.first, dy[d] + it.second};
if(S.find(nxt) != S.end())
unite(nxt, it);
}
for(auto it: li)
for(int d = 0; d < 2; d++)
{
pair<int, int> nxt = {dx[d] + it.first, dy[d] + it.second};
if(S.find(nxt) != S.end())
adj[root(nxt)].push_back(root(S[it]));
}
for(int i = 1; i <= n; i++)
{
sort(adj[i].begin(), adj[i].end());
adj[i].erase(unique(adj[i].begin(), adj[i].end()), adj[i].end());
}
r = root(1);
pre_dfs(r, r);
dfs(r, r);
return answer;
}
v
Compilation message
city.cpp:142:1: error: 'v' does not name a type
v
^
