Submission #1185063

#	Time	Username	Problem	Language	Result	Execution time	Memory
1185063		icebear	Janjetina (COCI21_janjetina)	C++20	110 / 110	254 ms	20104 KiB

Main

// ~~ icebear love attttt ~~
#include <bits/stdc++.h>
using namespace std;
#define int ll
typedef long long ll;
typedef pair<int, int> ii;
typedef pair<int, ii> iii;

template<class T>
    bool minimize(T &a, const T &b) {
        if (a > b) return a = b, true;
        return false;
    }

template<class T>
    bool maximize(T &a, const T &b) {
        if (a < b) return a = b, true;
        return false;
    }

#define FOR(i,a,b) for(int i=(a); i<=(b); ++i)
#define FORR(i,a,b) for(int i=(a); i>=(b); --i)
#define REP(i, n) for(int i=0; i<(n); ++i)
#define RED(i, n) for(int i=(n)-1; i>=0; --i)
#define MASK(i) (1LL << (i))
#define BIT(S, i) (((S) >> (i)) & 1)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define task "icebearat"

const int MOD = 1e9 + 7;
const int inf = 1e9 + 27092008;
const ll INF = 1e18 + 27092008;
const int N = 2e5 + 5;
int n, k;
vector<ii> G[N];
int ft[N], sz[N];
bool isCentroid[N];
ll ans = 0;
vector<ii> global_nodes, internal_nodes;

void update(int x, int val) {
    x++;
    for(; x < N; x += x & -x) ft[x] += val;
}

int query(int x) {
    x++;
    int res = 0;
    for(; x; x -= x & -x) res += ft[x];
    return res;
}

void dfs(int u, int par) {
    sz[u] = 1;
    for(ii v : G[u]) if (v.fi != par && !isCentroid[v.fi]) {
        dfs(v.fi, u);
        sz[u] += sz[v.fi];
    }
}

int findCentroid(int u, int par, const int &subtreeSize) {
    for(ii v : G[u]) if (v.fi != par && !isCentroid[v.fi] && sz[v.fi] > subtreeSize / 2)
        return findCentroid(v.fi, u, subtreeSize);
    return u;
}

void solve(vector<ii> &nodes, int sign) {
    ll sum = 0;
    sort(all(nodes));
    for(ii p : nodes) {
        if (p.fi - p.se >= 0) sum += query(p.fi - p.se);
        update(p.se, +1);
    }
    for(ii p : nodes) update(p.se, -1);
    ans += sum * sign;
}

void add_node(int u, int par, int maxW, int depth) {
    global_nodes.emplace_back(maxW, depth);
    internal_nodes.emplace_back(maxW, depth);

    for(ii v : G[u]) if (v.fi != par && !isCentroid[v.fi])
        add_node(v.fi, u, max(maxW, v.se), depth + 1);
}

void buildCentroid(int u) {
    dfs(u, -1);
    int centroid = findCentroid(u, -1, sz[u]);

    global_nodes.emplace_back(0, 0);
    for(ii v : G[centroid]) if (!isCentroid[v.fi]) {
        add_node(v.fi, centroid, v.se, 1);
        solve(internal_nodes, -1);
        internal_nodes.clear();
    }
    solve(global_nodes, +1);
    global_nodes.clear();


    isCentroid[centroid] = true;
    for(ii v : G[centroid]) if (!isCentroid[v.fi])
        buildCentroid(v.fi);
}

void init(void) {
    cin >> n >> k;
    FOR(i, 2, n) {
        int u, v, w;
        cin >> u >> v >> w;
        w -= k;
        G[u].pb(mp(v, w));
        G[v].pb(mp(u, w));
    }
}

void process(void) {
    buildCentroid(1);
    cout << ans * 2;
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    if (fopen(task".inp", "r")) {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    int tc = 1;
//    cin >> tc;
    while(tc--) {
        init();
        process();
    }
    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:129:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  129 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:130:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  130 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 35 / 35
• Subtask 3: 60 / 60