Submission #1199322

#	Time	Username	Problem	Language	Result	Execution time	Memory
1199322		Hamed_Ghaffari	Dreaming (IOI13_dreaming)	C++20	100 / 100	48 ms	15820 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;

using pii = pair<int, int>;

#define SZ(x) int(x.size())

const int MXN = 1e5+5;

vector<pii> g[MXN];
int dp[MXN];
bool vis[MXN];
vector<int> vec;

void dfs(int v, int p=-1) {
    vis[v] = 1;
    vec.push_back(v);
    for(auto [u, w] : g[v])
        if(u != p) {
            dfs(u, v);
            dp[v] = max(dp[v], dp[u]+w);
        }
}

void reroot(int v, int p=-1) {
    int mx1 = 0, mx2 = -1e9;
    for(auto [u, w] : g[v]) {
        int val = dp[u] + w;
        if(val>mx2) mx2=val;
        if(mx2>mx1) swap(mx1, mx2);
    }
    for(auto [u, w] : g[v])
        if(u!=p) {
            int val = dp[u] + w;
            dp[v] = val==mx1 ? mx2 : mx1;
            reroot(u, v);
        }
    dp[v] = mx1;
}

int travelTime(int n, int m, int l, int A[], int B[], int T[]) {
    for(int i=0; i<m; i++) {
        g[A[i]].push_back({B[i], T[i]});
        g[B[i]].push_back({A[i], T[i]});
    }
    vector<int> diams;
    for(int i=0; i<n; i++)
        if(!vis[i]) {
            dfs(i);
            reroot(i);
            int res=2e9;
            for(int v : vec)
                res = min(res, dp[v]);
            diams.push_back(res);
            vec.clear();
        }
    sort(diams.begin(), diams.end());
    int ans = *max_element(dp, dp+n);
    if(SZ(diams)>=2) ans = max(ans, diams[SZ(diams)-1]+diams[SZ(diams)-2]+l);
    if(SZ(diams)>=3)
        ans = max(ans, diams[SZ(diams)-2]+diams[SZ(diams)-3]+l+l);
    return ans;
}

• Subtask 1: 14 / 14
• Subtask 2: 10 / 10
• Subtask 3: 23 / 23
• Subtask 4: 18 / 18
• Subtask 5: 12 / 12
• Subtask 6: 23 / 23