Submission #481947

#	Time	Username	Problem	Language	Result	Execution time	Memory
481947		Sam_a17	Race (IOI11_race)	C++14	100 / 100	1063 ms	40976 KiB

race

#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
//#include "temp.cpp"
#include <cstdio>
using namespace std;

#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif

void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}

template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T> void print(T v[],T n) {cerr << "["; for(int i = 0; i < n; i++) {cerr << v[i] << " ";} cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}

#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'

// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5
void fastIO() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
    fastIO();

    if(str != "") {
        freopen((str + ".in").c_str(), "r", stdin);
        freopen((str + ".out").c_str(), "w", stdout);
    }
}
// Indexed Set
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int N = 2e5 + 10;
int n,k, answ = -1, sz[N], compSize;
vector<pair<int, int>> adj[N], mas;
bool used[N];
map<int, int> mp;

int dfs(int node = 1,int parent = 0) {
    sz[node] = 1, compSize++;
    for(auto i: adj[node]) {
        if(i.first != parent && !used[i.first]) {
            sz[node] += dfs(i.first, node);
        }
    }
    return sz[node];
}

int find_center(int node, int parent = 0) {
    for(auto i: adj[node]) {
        if(i.first != parent && !used[i.first]) {
            if(sz[i.first] * 2 > compSize) {
                return find_center(i.first, node);
            }
        }
    }
    return node;
}

int centroid(int a) {
    compSize = 0;
    dfs(a);
    int center = find_center(a);
    dfs(center);
    return center;
}

void solve(int node, int parent = 0, int l = 0, int d = 0) {
    if(parent) {
        mas.push_back({l, d});
    }

    for(auto i: adj[node]) {
        if(i.first != parent && !used[i.first]) {
            solve(i.first, node, l + i.second, d + 1);

            if(!parent) {
                for(auto j: mas) {
                    int L = j.first, D = j.second;
                    if(L > k) continue;
                    if(L == k) {
                        if(answ == -1 || answ > D) {
                            answ = D;
                        }
                    } else {
                        if(mp.find(k - L) != mp.end()) {
                            int ans = mp[k - L] + D;
                            if(answ == -1 || answ > ans) {
                                answ = ans;
                            }
                        }
                    }
                }

                for(auto j: mas) {
                    int L = j.first, D = j.second;
                    if(L > k) continue;
                    if(mp.find(L) != mp.end()) {
                        mp[L] = min(mp[L], D);
                    } else {
                        mp[L] = D;
                    }
                }
                mas.clear();
            }

        }
    }

}

void centroid_decomposition() {
    queue <int> q;
    q.push(1);

    while(!q.empty()) {
        auto a = q.front();
        q.pop();

        int center = centroid(a);
        solve(center);
        mp.clear();

        used[center] = 1;
        for(auto i: adj[center]) {
            if(!used[i.first] && sz[i.first] != 1) {
                q.push(i.first);
            }
        }

    }

}

int best_path(int M, int K, int H[][2], int L[]) {
    n = M, k = K;
    for(int i = 0; i < n - 1; i++) {
        int a = H[i][0], b = H[i][1], c = L[i]; a++, b++;
        adj[a].push_back({b, c});
        adj[b].push_back({a, c});
    }

    centroid_decomposition();

    return answ;
}

//
//int main () {
//    cin >> n >> k;
//
//    for(int i = 0; i < n - 1; i++) {
//        int a, b, c; cin >> a >> b >> c, a++, b++;
//        adj[a].push_back({b, c});
//        adj[b].push_back({a, c});
//    }
//
//    centroid_decomposition();
//
//    cout << answ << endl;
//    return 0;
//}

Compilation message (stderr)

race.cpp: In function 'void setIO(std::string)':
race.cpp:46:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   46 |         freopen((str + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
race.cpp:47:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |         freopen((str + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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