Submission #56146

#	Time	Username	Problem	Language	Result	Execution time	Memory
56146		win11905	Dreaming (IOI13_dreaming)	C++11	100 / 100	133 ms	17192 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
#define pii pair<int, int>
#define x first
#define y second
using namespace std;

const int N = 1e5+5, INF = 1e9+1;

vector<pair<int, pii> > g;
bool check[N];
int Answer;
pii Max1[N], Max2[N];

void dfs(int u, int p) {
    check[u] = true;
    auto x = lower_bound(g.begin(), g.end(), make_pair(u, pii(0, 0)));
    auto y = upper_bound(g.begin(), g.end(), make_pair(u, pii(INF, INF)));
    for(pii v = x->y; x != y; ++x, v = x->y) if(v.x != p) {
        dfs(v.x, u);
        pii ret(Max1[v.x].x + v.y, v.x);
        if(ret > Max1[u]) swap(ret, Max1[u]);
        if(ret > Max2[u]) swap(ret, Max2[u]);
    } 
    Answer = max(Answer, Max1[u].x + Max2[u].x);
} 

void find(int u, int p, int d, int &ret) {
    int now = max(Max1[u].x, d);
    if(now < ret) ret = now;
    auto x = lower_bound(g.begin(), g.end(), make_pair(u, pii(0, 0)));
    auto y = upper_bound(g.begin(), g.end(), make_pair(u, pii(INF, INF)));
    for(pii v = x->y; x != y; ++x, v = x->y) if(v.x != p) 
        find(v.x, u, max(d, Max1[u].y == v.x ? Max2[u].x : Max1[u].x) + v.y, ret);
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    g.reserve(M<<1|1);
    for(int i = 0; i < M; ++i) {
        g.emplace_back(A[i], pii(B[i], T[i]));
        g.emplace_back(B[i], pii(A[i], T[i]));
    }
    sort(g.begin(), g.end());
    vector<int> V;
    for(int i = 0; i < N; ++i) if(!check[i]) {   
        dfs(i, -1); 
        int shortest = INF;
        find(i, -1, 0, shortest);
        V.emplace_back(shortest);
    }
    sort(V.begin(), V.end(), greater<int>());
    if(V.size() >= 2) Answer = max(Answer, V[0] + V[1] + L);
    if(V.size() >= 3) Answer = max(Answer, V[1] + V[2] + L + L);
    return Answer;
}

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