Submission #1090122

#	Time	Username	Problem	Language	Result	Execution time	Memory
1090122		LilPluton	Race (IOI11_race)	C++14	0 / 100	6 ms	14428 KiB

race

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

const int sz = 2e5 + 5;
int n, res, k;
vector<vector<pair<int, int>>> adj(sz);
map<int, int> a[sz];
long long dep[sz], sum[sz];

void comp(int u, int p, long long  c, int h) {
	a[u][c] = h;
	sum[u] = c;
	dep[u] = h;
	for (auto n : adj[u]) {
		if (p == n.first) { continue; }
		comp(n.first, u, c + n.second, h + 1);
	}
}

void dfs(int v, int p) {
    int t = k + 2 * sum[v];
    for (auto i : adj[v]) {
        if (i.first == p) {
            continue;
        }
        if (a[i.first].size() > a[v].size()) {
            swap(a[i.first], a[v]);
        }
        for (auto j : a[i.first]) {
            if (a[v].find(t - j.first) != a[v].end()) {
                res = min(1LL * res, a[v][t - j.first] + j.second - 2 * dep[v]);
            }
        }
        for (auto j : a[i.first]) {
            if (a[v].find(j.first) == a[v].end()) {
                a[v].insert(j);
            } else {
                a[v][j.first] = min(a[v][j.first], j.second);
            }
        }
    }
}

int best_path(int N, int K, int H[][2], int L[]) {
    if (K == 1) {
        return 0;
    }
    n = N;
    k = K;
    for (int i = 0; i < N; ++i) {
        adj[i].clear();
        a[i].clear();
    }
    
    for (int i = 0; i < N - 1; ++i) {
        adj[H[i][0]].push_back({H[i][1], L[i]});
        adj[H[i][1]].push_back({H[i][0], L[i]});
    }
    
    res = INT_MAX;
    comp(0, -1, 0, 0);
    dfs(0, -1);
    
    return (res == INT_MAX ? -1 : res);
}

• Subtask 1: 0 / 9
• Subtask 2: 0 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57