#include <bits/stdc++.h>
using namespace std;
// macros
typedef long long ll;
typedef long double ld;
typedef pair<int, int> ii;
typedef pair<ll, ll> lll;
typedef tuple<int, int, int> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<iii> viii;
typedef vector<ll> vll;
typedef vector<lll> vlll;
#define REP(a,b,c) for(int a=int(b); a<int(c); a++)
#define RE(a,c) REP(a,0,c)
#define RE1(a,c) REP(a,1,c+1)
#define REI(a,b,c) REP(a,b,c+1)
#define REV(a,b,c) for(int a=int(c-1); a>=int(b); a--)
#define FOR(a,b) for(auto& a : b)
#define all(a) a.begin(), a.end()
#define INF 1e18
#define EPS 1e-9
#define pb push_back
#define popb pop_back
#define fi first
#define se second
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
// input
template<class T> void IN(T& x) {cin >> x;}
template<class H, class... T> void IN(H& h, T&... t) {IN(h); IN(t...); }
// output
template<class T1, class T2> void OUT(const pair<T1,T2>& x);
template<class T> void OUT(const vector<T>& x);
template<class T> void OUT(const T& x) {cout << x;}
template<class H, class... T> void OUT(const H& h, const T&... t) {OUT(h); OUT(t...); }
template<class T1, class T2> void OUT(const pair<T1,T2>& x) {OUT(x.fi,' ',x.se);}
template<class T> void OUT(const vector<T>& x) {RE(i,x.size()) OUT(i==0?"":" ",x[i]);}
template<class... T> void OUTL(const T&... t) {OUT(t..., "\n"); }
template<class H> void OUTLS(const H& h) {OUTL(h); }
template<class H, class... T> void OUTLS(const H& h, const T&... t) {OUT(h,' '); OUTLS(t...); }
// dp
template<class T> bool ckmin(T&a, T&b) { bool bl = a > b; a = min(a,b); return bl;}
template<class T> bool ckmax(T&a, T&b) { bool bl = a < b; a = max(a,b); return bl;}
void program();
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
program();
}
//===================//
// begin program //
//===================//
const int MX = 1e6+8;
const int N = (1<<20);
int n, edges;
int l[MX];
vii adj[MX];
// finding cycles
bitset<MX> visited;
int cycleStart;
int skippedEdge = -1;
vii cycle;
bool dfsVisit(int u, int pe) {
if(visited[u]) {
cycleStart = u;
skippedEdge = pe;
return true;
}
bool res = false;
visited[u] = 1;
FOR(e,adj[u]) {
if(e.se == pe || e.se == skippedEdge) continue;
if(!dfsVisit(e.fi, e.se^1)) continue;
cycle.pb({e.fi, l[e.se/2]});
res = u != cycleStart;
}
return res;
}
// finding depth
ll curBest = 0;
lll combine(lll x, ll y) {return {max(x.fi,y), max(min(x.fi,y),x.se)};}
int i1, i2;
ll dfsDepth(int u, int pe) {
ll res = 0;
lll p = {0,0};
FOR(e,adj[u]) {
if(e.se == pe) continue;
if(e.fi == i1) continue;
if(e.fi == i2) continue;
ll d = l[e.se/2] + dfsDepth(e.fi,e.se^1);
res = max(res, d);
p = combine(p,d);
}
curBest = max(curBest, p.fi + p.se);
return res;
}
void program() {
IN(n);
RE1(b,n) {
int a; IN(a,l[b-1]);
adj[a].pb({b,edges++});
adj[b].pb({a,edges++});
}
ll ans = 0;
RE1(i,n) {
if(visited[i]) continue;
// find the cycle
curBest = 0;
cycle.clear();
dfsVisit(i,-1);
// fill a, b and c
ll m = cycle.size(), totB = 0;
FOR(u,cycle) totB += u.se;
ll curB = totB;
ll bestSum1 = -INF, bestSum2 = -INF;
REV(i,0,m) {
curB -= cycle[i].se;
i1 = cycle[(i+1)%m].fi;
i2 = cycle[(i-1+m)%m].fi;
ll C = dfsDepth(cycle[i].fi, -1);
curBest = max(curBest , bestSum1 - curB + C);
curBest = max(curBest , totB + bestSum2 + curB + C);
bestSum1 = max(bestSum1, curB + C);
bestSum2 = max(bestSum2, -curB + C);
}
ans += curBest;
}
OUTL(ans);
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
15 ms |
23756 KB |
Output is correct |
| 2 |
Correct |
16 ms |
23756 KB |
Output is correct |
| 3 |
Correct |
16 ms |
23784 KB |
Output is correct |
| 4 |
Correct |
16 ms |
23704 KB |
Output is correct |
| 5 |
Correct |
16 ms |
23736 KB |
Output is correct |
| 6 |
Correct |
17 ms |
23772 KB |
Output is correct |
| 7 |
Correct |
16 ms |
23812 KB |
Output is correct |
| 8 |
Correct |
17 ms |
23816 KB |
Output is correct |
| 9 |
Correct |
15 ms |
23704 KB |
Output is correct |
| 10 |
Correct |
16 ms |
23728 KB |
Output is correct |
| 11 |
Correct |
15 ms |
23820 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
17 ms |
23860 KB |
Output is correct |
| 2 |
Correct |
16 ms |
23860 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
17 ms |
23884 KB |
Output is correct |
| 2 |
Correct |
18 ms |
24064 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
23 ms |
24548 KB |
Output is correct |
| 2 |
Correct |
33 ms |
26680 KB |
Output is correct |
| 3 |
Correct |
26 ms |
24652 KB |
Output is correct |
| 4 |
Correct |
20 ms |
24140 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
39 ms |
27860 KB |
Output is correct |
| 2 |
Correct |
49 ms |
29508 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
95 ms |
33896 KB |
Output is correct |
| 2 |
Correct |
92 ms |
38640 KB |
Output is correct |
| 3 |
Correct |
118 ms |
48148 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
146 ms |
41188 KB |
Output is correct |
| 2 |
Correct |
192 ms |
62644 KB |
Output is correct |
| 3 |
Correct |
250 ms |
67660 KB |
Output is correct |
| 4 |
Correct |
267 ms |
85012 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
324 ms |
66956 KB |
Output is correct |
| 2 |
Correct |
762 ms |
108676 KB |
Output is correct |
| 3 |
Correct |
273 ms |
57920 KB |
Output is correct |
| 4 |
Correct |
360 ms |
92720 KB |
Output is correct |
| 5 |
Correct |
374 ms |
93356 KB |
Output is correct |
| 6 |
Correct |
1086 ms |
62964 KB |
Output is correct |
| 7 |
Correct |
398 ms |
127848 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
370 ms |
131076 KB |
Execution killed with signal 9 |
| 2 |
Halted |
0 ms |
0 KB |
- |
