#pragma GCC target ("sse4")
#include <bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#include "dreaming.h"
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;
typedef pair<int, pi> pii;
typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;
#define fax(i, a) for (int i = 0; i < (a); i++)
#define f0x(i, a, b) for (int i = (a); i < (b); i++)
#define f0xd(i,a,b) for (int i = (b)-1; i >= (a); i--)
#define faxd(i,a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto& a : x)
#define memeset memset
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rsz resize
template<class T> void ckmin(T &a, T b) { a = min(a, b); }
template<class T> void ckmax(T &a, T b) { a = max(a, b); }
template <class T, int ...Ns> struct BIT {
T val = 0;
void upd(T v) { val += v; }
T query() { return val; }
};
template <class T, int N, int... Ns> struct BIT<T, N, Ns...> {
BIT<T,Ns...> bit[N + 1];
template<typename... Args> void upd(int pos, Args... args) {
for (; pos <= N; pos += (pos&-pos)) bit[pos].upd(args...);
}
template<typename... Args> T sum(int r, Args... args) {
T res = 0; for (; r; r -= (r&-r)) res += bit[r].query(args...);
return res;
}
template<typename... Args> T query(int l, int r, Args... args) {
return sum(r,args...)-sum(l-1,args...);
}
};
namespace input {
template<class T> void re(complex<T>& x);
template<class T1, class T2> void re(pair<T1,T2>& p);
template<class T> void re(vector<T>& a);
template<class T, size_t SZ> void re(array<T,SZ>& a);
template<class T> void re(T& x) { cin >> x; }
void re(double& x) { string t; re(t); x = stod(t); }
void re(ld& x) { string t; re(t); x = stold(t); }
template<class T, class... Ts> void re(T& t, Ts&... ts) {
re(t); re(ts...);
}
template<class T> void re(complex<T>& x) { T a,b; re(a,b); x = cd(a,b); }
template<class T1, class T2> void re(pair<T1,T2>& p) { re(p.f,p.s); }
template<class T> void re(vector<T>& a) { fax(i,sz(a)) re(a[i]); }
template<class T, size_t SZ> void re(array<T,SZ>& a) { fax(i,SZ) re(a[i]); }
}
using namespace input;
namespace output {
void pr(int x) { cout << x; }
void pr(long x) { cout << x; }
void pr(ll x) { cout << x; }
void pr(unsigned x) { cout << x; }
void pr(unsigned long x) { cout << x; }
void pr(unsigned long long x) { cout << x; }
void pr(float x) { cout << x; }
void pr(double x) { cout << x; }
void pr(ld x) { cout << x; }
void pr(char x) { cout << x; }
void pr(const char* x) { cout << x; }
void pr(const string& x) { cout << x; }
void pr(bool x) { pr(x ? "true" : "false"); }
template<class T1, class T2> void pr(const pair<T1,T2>& x);
template<class T> void pr(const T& x);
template<class T, class... Ts> void pr(const T& t, const Ts&... ts) {
pr(t); pr(ts...);
}
template<class T1, class T2> void pr(const pair<T1,T2>& x) {
pr("{",x.f,", ",x.s,"}");
}
template<class T> void pr(const T& x) {
pr("{"); // const iterator needed for vector<bool>
bool fst = 1; for (const auto& a: x) pr(!fst?", ":"",a), fst = 0;
pr("}");
}
void ps() { pr("\n"); } // print w/ spaces
template<class T, class... Ts> void ps(const T& t, const Ts&... ts) {
pr(t); if (sizeof...(ts)) pr(" "); ps(ts...);
}
void pc() { pr("]\n"); } // debug w/ commas
template<class T, class... Ts> void pc(const T& t, const Ts&... ts) {
pr(t); if (sizeof...(ts)) pr(", "); pc(ts...);
}
#define dbg(x...) pr("[",#x,"] = ["), pc(x);
}
using namespace output;
namespace io {
void setIn(string s) { freopen(s.c_str(),"r",stdin); }
void setOut(string s) { freopen(s.c_str(),"w",stdout); }
void setIO(string s = "") {
ios_base::sync_with_stdio(0); cin.tie(0); // fast I/O
if (sz(s)) { setIn(s+".in"), setOut(s+".out"); } // for USACO
}
}
using namespace io;
mt19937 rnd(chrono::high_resolution_clock::now().time_since_epoch().count());
const int MOD = 1000000007; // 998244353
const ll INF = 1e18;
const int MX = 200005;
const ld PI = 4*atan((ld)1);
vpi adj[MX]; int dp1[MX], dp2[MX], ans[MX], val[MX], par[MX];
void dfs1(int v, int p){
for(pi to : adj[v]){
if(to.f != p){
dfs1(to.f, v);
dp1[v] = max(dp1[v], dp1[to.f]+to.s);
val[to.f] = to.s;
par[to.f] = v;
}
}
}
void dfs2(int v, int p){
if(p != -1){
dp2[v] = max(dp2[v], dp2[p]+val[v]);
for(pi to2 : adj[p]){
if(to2.f != v && to2.f != par[p]){
dp2[v] = max(dp2[v], dp1[to2.f] + val[v] + to2.s);
}
}
}
for(pi to : adj[v]){
if(to.f != p){
dfs2(to.f, v);
}
}
}
bool vis[MX];
pi dfs_ans(int v, int p){
vis[v] = true;
pi ret = mp(max(dp1[v], dp2[v]), v);
for(pi to : adj[v]){
if(to.f != p){
pi nxt = dfs_ans(to.f, v);
ckmin(ret, nxt);
}
}
return ret;
}
pi dfs(int v, int p, int d){
pi best = mp(d,v);
for(pi to : adj[v]){
if(to.f != p){
ckmax(best, dfs(to.f, v, d+to.s));
}
}
return best;
}
int diam(int v, int p){
pi far = dfs(0,-1, 0);
return dfs(far.s, -1, 0).f;
}
int travelTime(int N, int M, int L, vi a, vi b, vi c){
fax(i,M){
//dbg(a[i], b[i], c[i]);
adj[a[i]].pb(mp(b[i],c[i]));
adj[b[i]].pb(mp(a[i],c[i]));
}
vpi roots;
fax(i,N){
if(!vis[i]){
dfs1(i,-1); dfs2(i,-1);
pi fin = dfs_ans(i,-1);
roots.pb(mp(fin.f, fin.s));
}
}
sort(all(roots));
//dbg(roots);
fax(i,sz(roots)-1){
int u = roots[sz(roots)-1].s; int v = roots[i].s; int w = L;
//dbg(u,v,w);
adj[u].pb(mp(v,w));
adj[v].pb(mp(u,w));
}
return diam(0,-1);
}
Compilation message
dreaming.cpp: In function 'void io::setIn(std::__cxx11::string)':
dreaming.cpp:134:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
void setIn(string s) { freopen(s.c_str(),"r",stdin); }
~~~~~~~^~~~~~~~~~~~~~~~~~~~~
dreaming.cpp: In function 'void io::setOut(std::__cxx11::string)':
dreaming.cpp:135:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
void setOut(string s) { freopen(s.c_str(),"w",stdout); }
~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
/tmp/ccw1nrA1.o: In function `main':
grader.c:(.text.startup+0xa2): undefined reference to `travelTime'
collect2: error: ld returned 1 exit status
