Submission #784667

#	Time	Username	Problem	Language	Result	Execution time	Memory
784667		vjudge1	Race (IOI11_race)	C++17	0 / 100	1186 ms	262144 KiB

race

#include <bits/stdc++.h>
#include "race.h"

using namespace std;

#define endl '\n'
#define ll long long
#define all(x) x.begin(), x.end()

vector<pair<int, int>> g[200005];
bool processed[200005];
int sz[200005];

int getSize(int cur, int par = -1) {
    sz[cur] = 1;
    for (auto next : g[cur]) {
        if (next.first != par && !processed[next.first]) sz[cur] += getSize(next.first, cur);
    }
    return sz[cur];
}

int getCentroid(int cur, int des, int par = -1) {
    for (auto next : g[cur]) {
        if (next.first != par && !processed[cur] && sz[cur] > des / 2) return getCentroid(next.first, des, cur);
    }
    return cur;
}

int ans = 10e7, k;

unordered_map<int, int> cnt;

void solve(int cur, int par, int depth, int sum, bool t) {
    if (sum > k || depth >= ans) return;
    if (sum == k) {
        ans = depth;
        return;
    }
    if (!t) {
        if (cnt.count(k - sum)) ans = min(ans, depth + cnt[k - sum]);
    }
    else {
        if (!cnt.count(sum)) cnt[sum] = depth;
        else cnt[sum] = min(cnt[sum], depth);
    }
    for (auto next : g[cur]) {
        if (next.first != par && !processed[next.first] && sum + next.second <= k) {
            solve(next.first, cur, depth + 1, sum + next.second, t);
        }
    }
}

void decompose(int cur = 0) {
    getSize(cur);
    cur = getCentroid(cur, getSize(cur));
    processed[cur] = 1;
    for (auto next : g[cur]) {
        if (!processed[next.first] && next.second <= k) {
            solve(cur, -1, 1, next.second, 0);
            solve(cur, -1, 1, next.second, 1);
        }
    }
    cnt.clear();
    for (auto next : g[cur]) {
        if (!processed[next.first]) decompose(next.first);
    }
}

int best_path(int N, int K, int H[][2], int L[]) {
    k = K;
    ans = N;
    for (int i = 0; i < N - 1; i++) {
        g[H[i][0]].push_back({H[i][1], L[i]});
        g[H[i][1]].push_back({H[i][0], L[i]});
    } 
    decompose();
    if (ans == N) return -1;
    else return ans;
}

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