| # |
Submission time |
Handle |
Problem |
Language |
Result |
Execution time |
Memory |
| 407251 |
2021-05-18T16:34:11 Z |
Aldas25 |
Islands (IOI08_islands) |
C++14 |
|
519 ms |
131076 KB |
#pragma GCC optimize("O2")
#include <bits/stdc++.h>
using namespace std;
#define FAST_IO ios_base::sync_with_stdio(0); cin.tie(0)
#define FOR(i, a, b) for(int i = (a); i <= (b); i++)
#define REP(n) FOR(O, 1, (n))
#define pb push_back
#define f first
#define s second
typedef long double ld;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<int, pii> piii;
typedef vector<int> vi;
typedef vector<pii> vii;
typedef vector<ll> vl;
typedef vector<piii> viii;
const int MAXN = 1000100, MAXK = 30;
//const ll MOD = 998244353;
const ll INF = 1e17;
const ld PI = asin(1) * 2;
int n;
vii adj[MAXN];
ll dp[MAXN][2];
bool inCycle[MAXN];
bool vis[MAXN];
stack<int> st;
vi cycle;
ll cycleWalkLen = 0;
ll enterD[MAXN];
void dfs1 (int v, int p = -1) {
vis[v] = true;
st.push(v);
for (auto pp : adj[v]) {
int u = pp.f;
ll l = pp.s;
if (u == p) {
p = -1;
continue;
}
if (!vis[u]) {
enterD[u] = enterD[v] + l;
dfs1(u, v);
}
else {
if ((int)cycle.size() == 0) {
cycleWalkLen = enterD[v] - enterD[u] + l;
while (st.top() != u) {
cycle.pb(st.top());
//cout << " pushing " << st.top();
st.pop();
}
cycle.pb(u);
// cout << " pushing u = "<<u<< endl;
}
}
}
if(!st.empty()) st.pop();
}
ll mxPath = 0;
void dfs2(int v,int p = -1) {
for (auto pp : adj[v]) {
int u = pp.f;
ll l = pp.s;
if (inCycle[u] || u == p) continue;
dfs2(u, v);
ll cr = dp[u][0] + l;
if (cr > dp[v][0]) {
dp[v][1] = dp[v][0];
dp[v][0] = cr;
} else if (cr > dp[v][1]) {
dp[v][1] = cr;
}
}
mxPath = max(mxPath, dp[v][0] + dp[v][1]);
}
int to[MAXN]; ll toLen[MAXN];
ll pref[MAXN];
ll getW (int a, int b) {
//cout << " getW a = " << a <<" b = " << b << endl;
//cout << " toA = " << to[a] << " toB = " << to[b] << endl;
if (to[a] != b) swap(a,b);
//cout << " b=" << b << "-> " << " a=" << a << " to[b] = " << to[b] << " tolen[b] = " << toLen[b]
//<< endl;
return toLen[a];
}
int main()
{
FAST_IO;
cin >> n;
FOR(i, 1, n) {
int u; ll l; cin >> u >> l;
to[i] = u; toLen[i] = l;
adj[i].pb({u, l});
adj[u].pb({i, l});
}
ll ans = 0;
FOR(i, 1, n) {
if (vis[i]) continue;
// cout << " i = " << i << endl;
cycle.clear();
cycleWalkLen = 0;
dfs1(i);
int len = (int)cycle.size();
for (int x : cycle) {
inCycle[x] = true;
//cout << " incycle x=" << x << endl;
}
FOR(a, 1, len-1) {
int v = cycle[a];
int pr = cycle[a-1];
pref[a] = pref[a-1] + getW (v, pr);
// cout << " pref[" << a << "] = " << pref[a] << endl;
// cout << " v = " << v << " pr = " << pr << " getw = " << getW(v,pr) << endl;
}
ll curMax = 0;
//cout << " cycleWalkLen = " << cycleWalkLen << endl;
for (int x : cycle) {
mxPath = 0;
dfs2(x);
curMax = max(curMax, mxPath);
//cout << " x = " << x << " mxPath = " << mxPath << endl;
}
ll mx1 = -INF;
ll mx2 = -INF;
FOR(b, 0, len-1) {
if (b>0) {
ll cr = dp[cycle[b]][0];
//cr += max(pref[b] - pref[a], cycleWalkLen-pref[b]+pref[a]);
cr += max(mx1 + pref[b], mx2 + cycleWalkLen-pref[b]);
curMax = max(curMax, cr);
}
mx1 = max(mx1, dp[cycle[b]][0] - pref[b]);
mx2 = max(mx2, dp[cycle[b]][0] + pref[b]);
//cout << " a = " << a << " b = " << b << " u=" << cycle[a] << " v=" << cycle[b] <<" cr=" << cr << endl;
}
ans += curMax;
}
cout << ans << "\n";
return 0;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
14 ms |
23756 KB |
Output is correct |
| 2 |
Correct |
14 ms |
23756 KB |
Output is correct |
| 3 |
Correct |
13 ms |
23884 KB |
Output is correct |
| 4 |
Correct |
13 ms |
23768 KB |
Output is correct |
| 5 |
Correct |
13 ms |
23852 KB |
Output is correct |
| 6 |
Correct |
14 ms |
23756 KB |
Output is correct |
| 7 |
Correct |
14 ms |
23784 KB |
Output is correct |
| 8 |
Correct |
14 ms |
23756 KB |
Output is correct |
| 9 |
Correct |
14 ms |
23756 KB |
Output is correct |
| 10 |
Correct |
13 ms |
23756 KB |
Output is correct |
| 11 |
Correct |
14 ms |
23756 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
14 ms |
24036 KB |
Output is correct |
| 2 |
Correct |
14 ms |
23924 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
14 ms |
23884 KB |
Output is correct |
| 2 |
Correct |
16 ms |
24280 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
20 ms |
25164 KB |
Output is correct |
| 2 |
Correct |
31 ms |
28144 KB |
Output is correct |
| 3 |
Correct |
24 ms |
25428 KB |
Output is correct |
| 4 |
Correct |
19 ms |
24568 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
38 ms |
29812 KB |
Output is correct |
| 2 |
Correct |
50 ms |
32660 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
96 ms |
40900 KB |
Output is correct |
| 2 |
Correct |
109 ms |
45700 KB |
Output is correct |
| 3 |
Correct |
126 ms |
62764 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
165 ms |
53272 KB |
Output is correct |
| 2 |
Correct |
217 ms |
83376 KB |
Output is correct |
| 3 |
Correct |
233 ms |
91196 KB |
Output is correct |
| 4 |
Correct |
286 ms |
123488 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
344 ms |
83496 KB |
Output is correct |
| 2 |
Runtime error |
519 ms |
131072 KB |
Execution killed with signal 9 |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
362 ms |
131076 KB |
Execution killed with signal 9 |
| 2 |
Halted |
0 ms |
0 KB |
- |
