# |
Submission time |
Handle |
Problem |
Language |
Result |
Execution time |
Memory |
407242 |
2021-05-18T16:29:07 Z |
Aldas25 |
Islands (IOI08_islands) |
C++14 |
|
2000 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;
}
FOR(a, 0, len-1) FOR(b, a+1, len-1) {
ll cr = dp[cycle[a]][0] + dp[cycle[b]][0];
cr += max(pref[b] - pref[a], cycleWalkLen-pref[b]+pref[a]);
curMax = max(curMax, cr);
//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 |
23804 KB |
Output is correct |
2 |
Correct |
14 ms |
23848 KB |
Output is correct |
3 |
Correct |
14 ms |
23860 KB |
Output is correct |
4 |
Correct |
14 ms |
23776 KB |
Output is correct |
5 |
Correct |
13 ms |
23776 KB |
Output is correct |
6 |
Correct |
14 ms |
23756 KB |
Output is correct |
7 |
Correct |
14 ms |
23756 KB |
Output is correct |
8 |
Correct |
14 ms |
23836 KB |
Output is correct |
9 |
Correct |
14 ms |
23824 KB |
Output is correct |
10 |
Correct |
14 ms |
23756 KB |
Output is correct |
11 |
Correct |
14 ms |
23820 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
14 ms |
23904 KB |
Output is correct |
2 |
Correct |
14 ms |
23948 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
15 ms |
23960 KB |
Output is correct |
2 |
Correct |
21 ms |
24396 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
35 ms |
25320 KB |
Output is correct |
2 |
Correct |
438 ms |
28628 KB |
Output is correct |
3 |
Correct |
24 ms |
25628 KB |
Output is correct |
4 |
Correct |
19 ms |
24764 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
660 ms |
30544 KB |
Output is correct |
2 |
Correct |
764 ms |
33880 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
826 ms |
43392 KB |
Output is correct |
2 |
Execution timed out |
2078 ms |
45684 KB |
Time limit exceeded |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1862 ms |
58668 KB |
Output is correct |
2 |
Execution timed out |
2075 ms |
89036 KB |
Time limit exceeded |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
350 ms |
98968 KB |
Output is correct |
2 |
Runtime error |
519 ms |
131076 KB |
Execution killed with signal 9 |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
376 ms |
131076 KB |
Execution killed with signal 9 |
2 |
Halted |
0 ms |
0 KB |
- |