Submission #445596

#	Time	Username	Problem	Language	Result	Execution time	Memory
445596		JerryLiu06	Islands (IOI08_islands)	C++17	100 / 100	388 ms	44396 KiB

islands

#include <bits/stdc++.h>
 
using namespace std;
 
using ll = long long;
using ld = long double;
using db = double;
using str = string;
 
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;
 
using vi = vector<int>;
using vb = vector<bool>;
using vl = vector<ll>;
using vd = vector<db>;
using vs = vector<str>;
using vpi = vector<pi>;
using vpl = vector<pl>;
using vpd = vector<pd>;
 
#define mp make_pair
#define f first
#define s second
 
#define sz(x) (int)(x).size()
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define sor(x) sort(all(x))
#define rsz resize
#define ins insert 
#define ft front()
#define bk back()
#define pb push_back
#define pf push_front
 
#define lb lower_bound
#define ub upper_bound
 
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define R0F(i, a) ROF(i, 0, a)
#define EACH(a, x) for (auto& a : x)
 
ll cdiv(ll a, ll b) { return a / b + ((a ^ b) > 0 && a % b); }
ll fdiv(ll a, ll b) { return a / b - ((a ^ b) < 0 && a % b); }
 
template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
 
template<class T> void remDup(vector<T>& v) { sor(v); v.erase(unique(all(v)), v.end()); }
 
const int MOD = 1e9 + 7;
const int MX = 1e6 + 10;
const ll INF = 1e18;

int N; pi nxt[MX]; int deg[MX]; ll diam[MX], dist[MX], ans = 0;

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0);

    cin >> N; FOR(i, 1, N + 1) { int A, L; cin >> A >> L; nxt[i] = {A, L}; deg[A]++; }

    queue<int> Q; FOR(i, 1, N + 1) if (deg[i] == 0) Q.push(i);

    while (!Q.empty()) {
        int cur = Q.front(); Q.pop(); int par = nxt[cur].f; 
        
        ckmax(diam[par], max(diam[cur], dist[par] + dist[cur] + nxt[cur].s));

        ckmax(dist[par], dist[cur] + nxt[cur].s); deg[par]--; if (deg[par] == 0) Q.push(par);
    }
    FOR(i, 1, N + 1) if (deg[i] > 0) {

        ll maxDiam = 0, FT = -INF, BK = -INF; ll curDist = 0; ll MX1 = -INF, MX2 = -INF;

        for (int j = i; deg[j] > 0; j = nxt[j].f) {
            ckmax(maxDiam, diam[j]); ckmax(FT, curDist + dist[j] + MX1); ckmax(BK, -curDist + dist[j] + MX2);

            ckmax(MX1, dist[j] - curDist); ckmax(MX2, dist[j] + curDist); deg[j] = 0; curDist += nxt[j].s;
        }
        ans += max(maxDiam, max(FT, BK + curDist));
    }
    cout << ans;
}

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