Submission #1247949

#	Time	Username	Problem	Language	Result	Execution time	Memory
1247949		nekolie	Dreaming (IOI13_dreaming)	C++20	100 / 100	67 ms	16968 KiB

dreaming

// Fluixarata or Cyngulini?
// That is the question...
#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;

const int maxn = 100001, inf = (1<<30);
int dp[maxn][2], odp;
bool odw[maxn]; vector<pair<int,int>> tree[maxn];
void dfs(int v, int p) {
    odw[v] = true;
    int x = 0, y = 0;
    for (auto [u,w] : tree[v]) {
        if (u == p)
            continue;
        dfs(u,v), dp[v][0] = max(dp[v][0],dp[u][0]+w);
        if (dp[u][0]+w > x)
            y = x, x = dp[u][0]+w;
        else if (dp[u][0]+w > y)
            y = dp[u][0]+w;
    }
    odp = max(odp,x+y);
}
void dfs2(int v, int p, int &maks) {
    int opt = -inf; maks = min(maks,max(dp[v][0],dp[v][1]));
    for (auto [u,w] : tree[v])
        if (u != p)
            dp[u][1] = max(dp[v][1],opt)+w, opt = max(opt,dp[u][0]+w);
    reverse(tree[v].begin(),tree[v].end()), opt = -inf;
    for (auto [u,w] : tree[v])
        if (u != p)
            dp[u][1] = max(dp[u][1],opt+w), opt = max(opt,dp[u][0]+w), dfs2(u,v,maks);
}
int travelTime(int n, int m, int l, int A[], int B[], int T[]) {
    int x = -inf, y = -inf, z = -inf;
    for (int i = 0; i < m; i++)
        tree[A[i]+1].push_back({B[i]+1,T[i]}), tree[B[i]+1].push_back({A[i]+1,T[i]});
    for (int i = 1; i <= n; i++) {
        if (odw[i])
            continue;
        int maks = inf;
        dfs(i,0), dfs2(i,0,maks);
        if (maks > x)
            z = y, y = x, x = maks;
        else if (maks > y)
            z = y, y = maks;
        else if (maks > z)
            z = maks;
    }
    return max({odp,x+y+l,y+z+2*l});
}

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