//#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;
struct Path{
int to, cost;
Path(int _to, int _cost){
to = _to;
cost = _cost;
}
};
struct Node{
int p[20], d;
};
map<int, int> c[100001];
vector<Path> path[100001];
bool in[100001];
Node a[100001];
int mxdist, mxid;
void build(int v, int p){
in[v] = 1;
for(auto x : path[v]){
if(x.to == p) continue;
a[x.to].d = a[v].d + 1;
memset(a[x.to].p, -1, sizeof(a[x.to].p));
a[x.to].p[0] = v;
for(int i = 1; i < 20; i++){
int t = a[x.to].p[i - 1];
if(t == -1) break;
a[x.to].p[i] = a[t].p[i - 1];
}
}
}
int goUp(int v, int u){
for(int i = 0; i < 20; i++){
if(u & (1 << i)) v = a[v].p[i];
}
return v;
}
int lca(int v, int u){
int l = 0;
int r = min(a[v].d, a[u].d) + 1;
int m;
while(l + 1 != r){
m = (l + r) >> 1;
if(goUp(v, a[v].d - m) == goUp(u, a[u].d - m)) l = m;
else r = m;
}
return goUp(v, a[v].d - l);
}
void dfs(int v, int p, int d){
if(path[v].size() == 1 && p != -1){
if(d > mxdist){
mxdist = d;
mxid = v;
}
}
for(auto x : path[v]){
if(x.to == p) continue;
dfs(x.to, v, d + x.cost);
}
}
int go(int v){
if(path[v].size() == 0) return 0;
if(in[v]) return 0;
memset(a[v].p, -1, sizeof(a[v].p));
a[v].d = 0;
build(v, -1);
mxdist = 0;
mxid = v;
dfs(v, -1, 0);
mxdist = 0;
v = mxid;
dfs(v, -1, 0);
int u = mxid;
int o = lca(v, u);
int s = (mxdist + 1) >> 1;
int q = 0;
while(v != o){
q += c[v][a[v].p[0]];
if(q >= s){
return min(q, mxdist - q + c[u][a[v].p[0]]);
}
}
q = 0;
while(u != o){
q += c[u][a[u].p[0]];
if(q >= s){
return min(q, mxdist - q + c[u][a[u].p[0]]);
}
}
}
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
for(int i = 0; i < M; i++){
path[A[i]].push_back(Path(B[i], T[i]));
path[B[i]].push_back(Path(A[i], T[i]));
c[A[i]][B[i]] = T[i];
c[B[i]][A[i]] = T[i];
}
int mx = -1;
int mx2 = -1;
int s;
for(int i = 0; i < N; i++){
s = go(i);
if(s > mx){
mx2 = mx;
mx = s;
} else if(s > mx2) mx2 = s;
}
return L + mx + mx2;
}
Compilation message
dreaming.cpp: In function 'int go(int)':
dreaming.cpp:100:1: warning: control reaches end of non-void function [-Wreturn-type]
}
^
/tmp/ccYPwHMp.o: In function `main':
grader.c:(.text.startup+0xa2): undefined reference to `travelTime'
collect2: error: ld returned 1 exit status
