Submission #395586

#	Time	Username	Problem	Language	Result	Execution time	Memory
395586		MarcoMeijer	Islands (IOI08_islands)	C++14	12 / 100	2074 ms	131076 KiB

islands

#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();
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    program();
}
 
 
//===================//
//   begin program   //
//===================//
 
const int MX = 1e6+10;
const int N = (1<<20);

int n;
ll a[MX], l[MX];
vi adj[MX];
vii adjW[MX];


// finding cycles
bitset<MX> visited;
int cycleStart;
vii cycle;
bool dfsVisit(int u, int p) {
    if(visited[u]) {
        cycleStart = u;
        return true;
    }
    bool res = false;
    visited[u] = 1;
    int cnt = 0;
    FOR(v,adjW[u]) {
        if(v.fi != p || cnt) {
            if(dfsVisit(v.fi, u)) {
                cycle.pb({v.fi,v.se});
                if(u != cycleStart)
                    res = true;
            }
        } else {
            cnt++;
        }
    }
    return res;
}

// finding depth
int dfsDepth(int u, int p, int i1, int i2) {
    int res = 0;
    FOR(v,adjW[u]) {
        if(v.fi == p) continue;
        if(v.fi == i1) continue;
        if(v.fi == i2) continue;
        res = max(res, v.se + dfsDepth(v.fi,u,i1,i2));
    }
    return res;
}

void program() {
    IN(n);
    RE1(i,n) IN(a[i],l[i]);
    RE1(i,n) {
        adj [i   ].pb(a[i]);
        adj [a[i]].pb(i);
        adjW[i   ].pb({a[i],l[i]});
        adjW[a[i]].pb({i   ,l[i]});
    }

    ll ans = 0;
    RE1(i,n) {
        if(visited[i]) continue;
        cycle.clear();
        dfsVisit(i,-1);
        cycle.pop_back();
        vll a, b, c; b.pb(0);
        ll m = cycle.size(), totB = 0;
        ll curBest = 0;
        FOR(u,cycle) a.pb(u.fi), b.pb(u.se);
        RE(i,m) c.pb(dfsDepth(a[i], -1, a[(i+1)%m], a[(i-1+m)%m]));
        FOR(i,b) totB += i;
        RE(i,m) b[i+1] += b[i];

        RE(i,m) REP(j,i+1,m) {
            curBest = max(curBest, b[j]-b[i]+c[i]+c[j]);
            curBest = max(curBest, totB-b[j]+b[i]+c[i]+c[j]);
        }
        ans += curBest;
    }
    OUTL(ans);
}

• Subtask 1: 12 / 33
• Subtask 2: 0 / 3
• Subtask 3: 0 / 4
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10