Submission #941455

#	Time	Username	Problem	Language	Result	Execution time	Memory
941455		Mike_Vu	Race (IOI11_race)	C++14	100 / 100	218 ms	53324 KiB

race

#include<bits/stdc++.h>

using namespace std;

const int MAX = 1e6 + 5;
const int inf = 1e9;

int n, k, res = inf, sz[MAX], min_length[MAX];
bool deleted[MAX];
vector<int> undo_length;
vector<pair<int, int>> adj[MAX];
stack<pair<int, int>> updates;

int get_size(int u, int pre){
    sz[u] = 1;
    for(auto [v, w] : adj[u]) if(v != pre and !deleted[v]){
        sz[u] += get_size(v, u);
    }
    return sz[u];
}

int find_centroid(int u, int pre, int target){
    for(auto [v, w] : adj[u]) if(v != pre and !deleted[v] and sz[v] * 2 > target){
        return find_centroid(v, u, target);
    }
    return u;
}

void compute(int u, int pre, int len, int sum){
    if(sum > k) return;
    res = min(res, len + min_length[k - sum]);
    updates.push(make_pair(len, sum));
    for(auto [v, w] : adj[u]) if(v != pre and !deleted[v]){
        compute(v, u, len + 1, sum + w);
    }
}

void decompose(int u){
    int c = find_centroid(u, -1, get_size(u, -1));
    deleted[c] = true;

    undo_length.clear();
    for(auto [v, w] : adj[c]) if(!deleted[v]){
        compute(v, c, 1, w);
        while(!updates.empty()){
            int len, sum;
            tie(len, sum) = updates.top(); updates.pop();
            min_length[sum] = min(min_length[sum], len);
            undo_length.push_back(sum);
        }
    }

    for(auto v : undo_length) min_length[v] = inf;
    for(auto [v, w] : adj[c]) if(!deleted[v]){
        decompose(v);
    }
}

int best_path(int N, int K, int H[][2], int L[]){
    n = N; k = K;
    for(int i = 0; i < n - 1; ++i){
        int u = H[i][0], v = H[i][1], w = L[i];
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
    }

    fill(min_length + 1, min_length + 1 + k, inf);
    decompose(1);
    if(res >= inf) res = -1;
    return res;
}

//#define Zero_OP
#ifdef Zero_OP

void init(void){

}

void process(){
    int H[2][2];
    H[0][0] = 0;
    H[0][1] = 1;
    H[1][0] = 1;
    H[1][1] = 2;
    int L[2];
    L[0] = 1;
    L[1] = 1;
    cout << best_path(3, 3, H, L) << '\n';
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    init();
    process();

    return 0;
}
#endif

Compilation message (stderr)

race.cpp: In function 'int get_size(int, int)':
race.cpp:16:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   16 |     for(auto [v, w] : adj[u]) if(v != pre and !deleted[v]){
      |              ^
race.cpp: In function 'int find_centroid(int, int, int)':
race.cpp:23:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   23 |     for(auto [v, w] : adj[u]) if(v != pre and !deleted[v] and sz[v] * 2 > target){
      |              ^
race.cpp: In function 'void compute(int, int, int, int)':
race.cpp:33:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   33 |     for(auto [v, w] : adj[u]) if(v != pre and !deleted[v]){
      |              ^
race.cpp: In function 'void decompose(int)':
race.cpp:43:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   43 |     for(auto [v, w] : adj[c]) if(!deleted[v]){
      |              ^
race.cpp:54:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   54 |     for(auto [v, w] : adj[c]) if(!deleted[v]){
      |              ^

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