Submission #946053

#	Time	Username	Problem	Language	Result	Execution time	Memory
946053		sysia	Duathlon (APIO18_duathlon)	C++17	0 / 100	1093 ms	34504 KiB

count_triplets

//Sylwia Sapkowska
#include <bits/stdc++.h>
#pragma GCC optimize("O3", "unroll-loops")
using namespace std;

void __print(int x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << "'" << x << "'";}
void __print(const char *x) {cerr << '"' << x << '"';}
void __print(const string &x) {cerr << '"' << x << '"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ", "; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? ", " : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef LOCAL
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif

#define int long long
typedef pair<int, int> T;
const int oo = 1e18, oo2 = 1e9+7, K = 30;
const int mod = 998244353;

void solve(){
    int n, m; cin >> n >> m;
    vector<vector<int>>g(n+1);
    for (int i = 0; i<m; i++){
        int a, b; cin >> a >> b;
        g[a].emplace_back(b);
        g[a].emplace_back(b);
    }
    vector<int>depth(n+1);
    vector up(n+1, vector<int>(K));
    int c = 0;
    vector<int>vis(n+1);
    function<void(int, int)>dfs = [&](int v, int pa){
        up[v][0] = pa;
        vis[v] = c;
        for (int i = 1; i<K; i++) up[v][i] = up[up[v][i-1]][i-1];
        for (auto x: g[v]){
            if (x == pa) continue;
            depth[x] = depth[v]+1;
            dfs(x, v);
        }
    };
    for (int i = 1; i<=n;i++){
        if (!vis[i]){
            c++;
            dfs(i, i);
        }
    }
    auto lca = [&](int a, int b){
        if (depth[a] > depth[b]) swap(a, b);
        for (int i = K-1; i>=0; i--){
            if (depth[b] - (1<<i) >= depth[a]){
                b = up[b][i];
            }
        }
        if (a == b) return a;
        for (int i = K-1; i>=0; i--){
            if (up[a][i] != up[b][i]){
                a = up[a][i];
                b = up[b][i];
            }
        }
        return up[a][0];
    };
    auto D = [&](int a, int b){
        return max(0ll, depth[a] + depth[b] - 2 * depth[lca(a, b)] - 1);
    };
    int ans = 0;
    for (int i = 1; i<=n; i++){
        for (int j = 1; j<=n; j++){
            if (vis[i] == vis[j]){
                ans += D(i, j);
            }
        }
    }
    cout << ans << "\n";
}

int32_t main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int t = 1;
    //cin >> t;
    while (t--) solve();

    return 0;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 8
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 15
• Subtask 7: 0 / 20
• Subtask 8: 0 / 8
• Subtask 9: 0 / 10