제출 #887230

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
887230		amsraman	Race (IOI11_race)	C++17	100 / 100	973 ms	46164 KiB

race

#include <bits/stdc++.h>
 
using namespace std;
 
int best_path(int n, int k, int h[][2], int l[]) {
    int ans = n + 1;
    vector<int> sz(n); vector<bool> vis(n, false);
    vector<vector<pair<int, int>>> g(n);
    for(int i = 0; i < n - 1; i++) {
        g[h[i][0]].emplace_back(h[i][1], l[i]);
        g[h[i][1]].emplace_back(h[i][0], l[i]);
    }
    map<int, int> m1, m2;
    auto proc = [&](auto rec, int u, int p, int num, int sum) -> void {
        if(!m2.count(sum)) m2[sum] = num;
        else m2[sum] = min(m2[sum], num);
        for(auto [v, w]: g[u]) {
            if(v == p || vis[v]) continue;
            rec(rec, v, u, num + 1, sum + w);
        }
    };
    auto get_size = [&](auto rec, int u, int p = 0) -> int {
        sz[u] = 1;
        for(auto [v, w]: g[u]) {
            if(v != p && !vis[v]) {
                sz[u] += rec(rec, v, u);
            }
        }
        return sz[u];
    };
    auto find_centroid = [&](auto rec, int u, int p, int full_sz) -> int {
        for(auto [v, w]: g[u]) {
            if(v != p && !vis[v] && 2 * sz[v] > full_sz) {
                return rec(rec, v, u, full_sz);
            }
        }
        return u;
    };
    auto centroid_decomp = [&](auto rec, int u) -> void {
        get_size(get_size, u, u);
        u = find_centroid(find_centroid, u, u, sz[u]);
        get_size(get_size, u, u);
        vis[u] = true;
        m1[0] = 0;
        for(auto [v, w]: g[u]) {
            if(!vis[v]) {
                proc(proc, v, v, 1, w);
                for(auto [sum, num]: m2) {
                    if(m1.count(k - sum)) {
                        ans = min(ans, num + m1[k - sum]);
                    }
                }
                for(auto [sum, num]: m2) {
                    if(!m1.count(sum)) m1[sum] = num;
                    else m1[sum] = min(m1[sum], num);
                }
                m2.clear();
            }
        }
        m1.clear();
        for(auto [v, w]: g[u]) {
            if(!vis[v]) rec(rec, v);
        }
    };
    centroid_decomp(centroid_decomp, 0);
    return ans == n + 1 ? -1 : ans;
}

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