#include <bits/stdc++.h>
using namespace std;
#define OPTM ios_base::sync_with_stdio(0); cin.tie(0);
#define INF int64_t(1e9)
#define ln '\n'
#define ll long long
#define ull unsigned long long
#define ui unsigned int
#define us unsigned short
#define FOR(i,s,n) for (int i = s; i < n; i++)
#define FORR(i,n,s) for (int i = n; i > s; i--)
#define FORX(u, arr) for (auto u : arr)
#define PB push_back
#define in(v,x) (v.find(x) != v.end())
#define F first
#define S second
#define PII pair<int, int>
#define PLL pair<ll, ll>
#define UM unordered_map
#define US unordered_set
#define PQ priority_queue
#define ALL(v) v.begin(), v.end()
const ll LLINF = 1e18+1;
#define int long long
const int MAXN = 1e5+5;
int n;
UM<int,UM<int,int>> mp;
bool z[MAXN];
int comp[MAXN], sz[MAXN], dp[MAXN], num, res;
vector<pair<PII,int>> pts;
US<int> tojoin;
vector<int> v[MAXN];
void dfs(int x, int y) {
if (z[mp[y][x]]) return;
z[mp[y][x]] = 1;
comp[mp[y][x]] = num;
sz[num]++;
if (mp[y-1].count(x)) tojoin.insert(comp[mp[y-1][x]]);
if (mp[y].count(x+1)) dfs(x+1,y);
if (mp[y].count(x-1)) dfs(x-1,y);
}
void dfs1(int x, int y) {
if (z[mp[y][x]]) return;
z[mp[y][x]] = 1;
comp[mp[y][x]] = num;
sz[num]++;
if (mp[y].count(x-1)) tojoin.insert(comp[mp[y][x-1]]);
if (mp[y+1].count(x)) dfs1(x,y+1);
if (mp[y-1].count(x)) dfs1(x,y-1);
}
bool cmp(const pair<PII,int> &a, const pair<PII,int> &b) {
if (a.F.S == b.F.S) return a.F.F < b.F.F;
return a.F.S < b.F.S;
}
void dfs2(int s, int pa) {
dp[s] = sz[s];
FORX(u,v[s]) {
if (u == pa) continue;
dfs2(u,s);
dp[s] += dp[u];
}
}
void dfs3(int s, int pa) {
FORX(u,v[s]) {
if (u == pa) continue;
res = (res+(dp[u]*(dp[0]-dp[u]))%INF)%INF;
dfs3(u,s);
}
}
void reset() {
FOR(i,0,n+1) {
z[i] = comp[i] = sz[i] = dp[i] = 0LL;
v[i].clear();
}
num = 0LL;
}
void solve(int t) {
if (t == 0) sort(ALL(pts));
else sort(ALL(pts),cmp);
FOR(i,0,n) {
if (z[pts[i].S]) continue;
tojoin.clear();
if (t == 0) dfs(pts[i].F.S, pts[i].F.F);
else dfs1(pts[i].F.S, pts[i].F.F);
FORX(u,tojoin) {
v[num].PB(u);
v[u].PB(num);
}
num++;
}
dfs2(0,-1);
dfs3(0,-1);
}
signed main() {
OPTM;
cin >> n;
FOR(i,0,n) {
int y,x; cin >> y >> x;
pts.PB({{y,x},i});
mp[y][x] = i;
}
solve(0);
reset();
solve(1);
cout << res;
}
Compilation message
city.cpp: In function 'void reset()':
city.cpp:79:24: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
79 | z[i] = comp[i] = sz[i] = dp[i] = 0LL;
| ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
/usr/bin/ld: /tmp/ccy0fXiy.o: in function `main':
city.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/ccdWgLfA.o:grader.cpp:(.text.startup+0x0): first defined here
/usr/bin/ld: /tmp/ccdWgLfA.o: in function `main':
grader.cpp:(.text.startup+0x104): undefined reference to `DistanceSum(int, int*, int*)'
collect2: error: ld returned 1 exit status
