//Never stop trying
#include "bits/stdc++.h"
using namespace std;
#define boost ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)
typedef long long ll;
typedef string str;
typedef long double ld;
typedef pair<int, int> pi;
#define fi first
#define se second
typedef vector<int> vi;
typedef vector<pi> vpi;
#define pb push_back
#define eb emplace_back
#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define endl "\n"
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
const int MOD = 1e9 + 7; //998244353
const ll INF = 1e18;
const int MX = 1e6 + 10;
const int nx[4] = {0, 0, 1, -1}, ny[4] = {1, -1, 0, 0}; //right left down up
template<class T> bool ckmin(T& a, const T& b) { return a > b ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
ll cdiv(ll a, ll b) { return a / b + ((a ^ b) > 0 && a % b); } // divide a by b rounded up
//constexpr int log2(int x) { return 31 - __builtin_clz(x); } // floor(log2(x))
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
//mt19937_64 rng(chrono::system_clock::now().time_since_epoch().count());
ll random(ll a, ll b){
return a + rng() % (b - a + 1);
}
#ifndef LOCAL
#define cerr if(false) cerr
#endif
#define dbg(x) cerr << #x << " : " << x << endl;
#define dbgs(x,y) cerr << #x << " : " << x << " / " << #y << " : " << y << endl;
#define dbgv(v) cerr << #v << " : " << "[ "; for(auto it : v) cerr << it << ' '; cerr << ']' << endl;
#define here() cerr << "here" << endl;
void IO() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
}
/////////////////////////ONLY CLEAN CODES ALLOWED/////////////////////////
int N;
vpi adj[MX];
//------------------------------------
vi vis(MX,0),vec;
void dfs(int u){
if(vis[u]) return;
vis[u]=1;
vec.pb(u);
for(auto it: adj[u]){
int v=it.fi;
dfs(v);
}
}
//--------------------------------------
int p[MX];
int findSet(int u){
return p[u]==u ? u : p[u]=findSet(p[u]);
}
void joinSet(int u, int v){
u=findSet(u),v=findSet(v);
if(v==u) return;
p[v]=u;
}
//------------------------------------
int U,V,W;
vpi tree[MX];
vpi diam;
ll sum_diam;
ll dist[MX];
vpi par(MX);
void dfs2(int u){
for(auto it: tree[u]){
int v=it.fi,w=it.se;
if(dist[v]==-1){
dist[v]=dist[u]+w;
par[v]={u,w};
dfs2(v);
}
}
}
void build(){
//tree building
for(int u: vec){
p[u]=u;
}
for(int u: vec){
for(auto it: tree[u]){
int v=it.fi,w=it.se;
if(findSet(u)==findSet(v)){
sum_diam=0;
return;
}
}
}
here()
for(int u: vec){
for(auto it: tree[u]){
int v=it.fi,w=it.se;
if(u<v) dbgs(u,v)
}
}
//diameter building
int u=vec[0];
for(int v: vec) dist[v]=-1;
dist[u]=0; par[u]={-1,0};
dfs2(u);
int v=u;
for(int vp: vec) if(dist[vp]>dist[v]) v=vp;
u=v;
for(int v: vec) dist[v]=-1;
dist[u]=0; par[u]={-1,0};
dfs2(u);
v=u;
for(int vp: vec) if(dist[vp]>dist[v]) v=vp;
diam.clear();
while(1){
diam.eb(v,par[v].se);
if(v==u) break;
v=par[v].fi;
}
sum_diam=0;
for(auto it: diam){
sum_diam+=it.se;
}
}
//-------------------------------------
ll dist_diam[MX],pref[MX];
void dfs3(int u){
for(auto it: tree[u]){
int v=it.fi,w=it.se;
if(dist_diam[v]==-1){
dist_diam[v]=dist_diam[u]+w;
dfs3(v);
}
}
}
void compute(){
memset(dist_diam,-1,MX);
for(auto it: diam){
dist_diam[it.fi]=0;
}
int prev=-1,prevW=0;
for(auto it: diam){
int u=it.fi,w=it.se;
dfs3(u);
pref[u]=prevW;
if(prev!=-1){
pref[u]+=pref[prev];
}
prev=u;
prevW=w;
}
}
ll get(int U, int V){
return abs(pref[U]-pref[V]);
}
//------------------------------------
int main() {
boost; IO();
cin>>N;
FOR(i,1,N+1){
int j,w; cin>>j>>w;
adj[i].eb(j,w);
adj[j].eb(i,w);
}
ll ans=0;
FOR(i,1,N+1) if(!vis[i]){
vec.clear();
dfs(i);
vector<pair<pi,int>>ed;
for(int u: vec){
for(auto it: adj[u]){
int v=it.fi,w=it.se;
ed.pb({{u,v},w});
}
}
ll x=0;
//we are in a component
for(auto it: ed){
U=it.fi.fi,V=it.fi.se,W=it.se;
int done=0;
for(int u: vec) tree[u].clear();
for(int u: vec){
for(auto it: adj[u]) if(u<it.fi){
int v=it.fi,w=it.se;
if(u==U && v==V && w==W && !done){
done=1;
continue;
}
if(u==V && v==U && w==W && !done){
done=1;
continue;
}
tree[u].eb(v,w);
tree[v].eb(u,w);
}
}
build();
ckmax(x,sum_diam);
}
ans+=x;
}
cout << ans << endl;
return 0;
}
//Change your approach
Compilation message
islands.cpp: In function 'void build()':
islands.cpp:115:16: warning: unused variable 'w' [-Wunused-variable]
115 | int v=it.fi,w=it.se;
| ^
islands.cpp:126:16: warning: unused variable 'w' [-Wunused-variable]
126 | int v=it.fi,w=it.se;
| ^
islands.cpp: In function 'void compute()':
islands.cpp:177:24: warning: 'memset' used with length equal to number of elements without multiplication by element size [-Wmemset-elt-size]
177 | memset(dist_diam,-1,MX);
| ^
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
37 ms |
58956 KB |
Output is correct |
| 2 |
Correct |
43 ms |
59000 KB |
Output is correct |
| 3 |
Correct |
69 ms |
59124 KB |
Output is correct |
| 4 |
Correct |
38 ms |
58956 KB |
Output is correct |
| 5 |
Correct |
38 ms |
58956 KB |
Output is correct |
| 6 |
Correct |
38 ms |
59044 KB |
Output is correct |
| 7 |
Correct |
37 ms |
59000 KB |
Output is correct |
| 8 |
Correct |
37 ms |
58964 KB |
Output is correct |
| 9 |
Correct |
36 ms |
59048 KB |
Output is correct |
| 10 |
Correct |
40 ms |
59084 KB |
Output is correct |
| 11 |
Correct |
37 ms |
59064 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
224 ms |
59196 KB |
Output is correct |
| 2 |
Correct |
39 ms |
59084 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
41 ms |
59184 KB |
Output is correct |
| 2 |
Execution timed out |
2081 ms |
59592 KB |
Time limit exceeded |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Execution timed out |
2064 ms |
59972 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Execution timed out |
2081 ms |
66108 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Execution timed out |
2087 ms |
82596 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Execution timed out |
2079 ms |
75516 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
393 ms |
131072 KB |
Execution killed with signal 9 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
391 ms |
131072 KB |
Execution killed with signal 9 |
| 2 |
Halted |
0 ms |
0 KB |
- |
