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Submission #973815

# Submission time Handle Problem Language Result Execution time Memory
973815 2024-05-02T11:22:30 Z GrindMachine Islands (IOI08_islands) C++17
80 / 100
 397 ms 131072 KB 
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*



*/

const int MOD = 1e9 + 7;
const int N = 1e6 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

vector<pll> adj[N];
vector<bool> on_cyc(N,1);
vector<ll> mxd(N);

void dfs1(ll u, ll p){
    for(auto [v,w] : adj[u]){
        if(v == p or on_cyc[v]) conts;
        dfs1(v,u);
        amax(mxd[u],mxd[v]+w);
    }
}

pll diam;

void dfs2(ll u, ll p, ll d){
    pll px = {d,u};
    amax(diam,px);
    for(auto [v,w] : adj[u]){
        if(v == p or on_cyc[v]) conts;
        dfs2(v,u,d+w);
    }
}

void solve(int test_case)
{
    ll n; cin >> n;
    vector<ll> a(n+5), b(n+5);
    rep1(u,n){
        ll v,w; cin >> v >> w;
        a[u] = v;
        b[u] = w;
        adj[u].pb({v,w}), adj[v].pb({u,w});
    }

    queue<ll> q;
    vector<ll> indeg(n+5);
    rep1(i,n) indeg[a[i]]++;
    rep1(i,n){
        if(!indeg[i]){
            q.push(i);
        }
    }

    while(!q.empty()){
        ll u = q.front();
        q.pop();
        on_cyc[u] = 0;
        ll v = a[u];
        indeg[v]--;
        if(!indeg[v]){
            q.push(v);
        }
    }

    vector<bool> vis(n+5);
    ll ans = 0;

    rep1(i,n){
        if(!on_cyc[i]) conts;
        if(vis[i]) conts;
        
        ll j = i;
        vector<pll> nodes;
        vector<ll> weights;
        while(!vis[j]){
            vis[j] = 1;
            nodes.pb({j,-1});
            weights.pb(b[j]);
            j = a[j];
        }

        ll siz = sz(nodes);
        rep(j,siz){
            nodes[j].ss = weights[(j-1+siz)%siz];
        }

        vector<ll> p(siz);
        rep(j,siz){
            p[j] = nodes[j].ss;
            if(j) p[j] += p[j-1]; 
        }
        ll len = p.back();
        ll best = 0, mx1 = -inf2, mx2 = -inf2;

        rep(j,siz){
            ll u = nodes[j].ff;
            dfs1(u,-1);
            ll d = mxd[u];
            amax(best,d+p[j]+mx1);
            amax(best,d-p[j]+mx2+len);
            amax(mx1,d-p[j]);
            amax(mx2,d+p[j]);

            on_cyc[u] = 0;
            diam = {-1,-1};
            dfs2(u,-1,0);
            ll s = diam.ss;
            diam = {-1,-1};
            dfs2(s,-1,0);
            amax(best,diam.ff);
            on_cyc[u] = 1;
        }

        ans += best;
    }

    cout << ans << endl;
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 12 ms 31832 KB Output is correct
2 Correct 8 ms 31832 KB Output is correct
3 Correct 8 ms 31832 KB Output is correct
4 Correct 8 ms 31832 KB Output is correct
5 Correct 8 ms 31836 KB Output is correct
6 Correct 8 ms 31836 KB Output is correct
7 Correct 7 ms 31856 KB Output is correct
8 Correct 7 ms 31836 KB Output is correct
9 Correct 8 ms 32084 KB Output is correct
10 Correct 8 ms 31836 KB Output is correct
11 Correct 8 ms 31836 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 31832 KB Output is correct
2 Correct 10 ms 31836 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 31888 KB Output is correct
2 Correct 10 ms 32088 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 33116 KB Output is correct
2 Correct 20 ms 35236 KB Output is correct
3 Correct 16 ms 33372 KB Output is correct
4 Correct 12 ms 32604 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 24 ms 36444 KB Output is correct
2 Correct 35 ms 40296 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 76 ms 47700 KB Output is correct
2 Correct 77 ms 51428 KB Output is correct
3 Correct 90 ms 59420 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 128 ms 62452 KB Output is correct
2 Correct 152 ms 79600 KB Output is correct
3 Correct 164 ms 84680 KB Output is correct
4 Correct 202 ms 97096 KB Output is correct

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 247 ms 110504 KB Output is correct
2 Runtime error 397 ms 131072 KB Execution killed with signal 9
3 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 266 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -