Submission #1097403

#	Time	Username	Problem	Language	Result	Execution time	Memory
1097403		Whisper	Construction Project 2 (JOI24_ho_t2)	C++17	100 / 100	309 ms	27988 KiB

Main

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

#define int long long
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, a, b) for (int i = (b); i >= (a); i --)
#define REP(i, a) for (int i = 0; i < (a); ++i)
#define REPD(i, a) for (int i = (a) - 1; i >= 0; --i)

#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)


constexpr ll LINF = (1ll << 60);
constexpr int INF = (1ll << 30);
constexpr int Mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

/*
    Phu Trong from Nguyen Tat Thanh High School for gifted student
*/

template <class X, class Y>
    bool minimize(X &x, const Y &y){
        X eps = 1e-9;
        if (x > y + eps) {x = y; return 1;}
        return 0;
    }

template <class X, class Y>
    bool maximize(X &x, const Y &y){
        X eps = 1e-9;
        if (x + eps < y) {x = y; return 1;}
        return 0;
    }
#define MAX                         200005
int numNode, numEdge;
int from, to, length, minTime;

struct Edge{
    int u, v, w;
    Edge(){}
    Edge(int _u, int _v, int _w): u(_u), v(_v), w(_w){}

    int other(int x){
        return (x ^ u ^ v);
    }
} edge[MAX];
vector<int> G[MAX];

void dijkstra(int s, int minDist[]){
    for (int i = 1; i <= numNode; ++i) minDist[i] = LINF;
    minDist[s] = 0;
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> q;
    q.emplace(0, s);
    while(q.size()){
        int du, u; tie(du, u) = q.top();
        q.pop();
        if (du > minDist[u]) continue;
        for (int&i : G[u]){
            int v = edge[i].other(u);
            if(minimize(minDist[v], minDist[u] + edge[i].w)){
                q.emplace(minDist[v], v);
            }
        }
    }
}
int minDist[2][MAX];
vector<int> comp;
struct FenwickTree{
    vector<int> F;
    int n;
    FenwickTree(int _n = 0){
        this -> n = _n;
        F.resize(n + 5, 0);
    }
    int low_bit(int p){
        return p & -p;
    }
    void upd(int p, int v){
        for (; p <= n; p += low_bit(p)) F[p] += v;
    }
    int query(int p){
        int res = 0;
        for (; p > 0; p -= low_bit(p)) res += F[p];
        return res;
    }
};
int find(int x){
    return lower_bound(comp.begin(), comp.end(), x) - comp.begin() + 1;
}

void process(void){
    cin >> numNode >> numEdge >> from >> to;
    cin >> length >> minTime;
    //build a new road with length l
    //move from s -> t and does not exceed minTime

    //D(from, u) + l + D(v, to) <= minTime
    //-> D(from, u) <= minTime - l - D(v, to)
    for (int i = 1; i <= numEdge; ++i){
        cin >> edge[i].u >> edge[i].v >> edge[i].w;
        G[edge[i].u].emplace_back(i);
        G[edge[i].v].emplace_back(i);
    }

    dijkstra(from, minDist[0]);
    dijkstra(to,   minDist[1]);

    if(minDist[0][to] <= minTime){
        return void(cout << numNode * (numNode - 1) / 2);
    }

    for (int i = 1; i <= numNode; ++i){
        comp.emplace_back(minDist[0][i]);
        comp.emplace_back(minTime - minDist[1][i] - length);
    }
    sort(comp.begin(), comp.end());
    comp.resize(unique(comp.begin(), comp.end()) - comp.begin());
    FenwickTree ft((int)comp.size());

    for (int i = 1; i <= numNode; ++i){
        int value = find(minDist[0][i]);
        ft.upd(value, 1);
    }
    int ans = 0;
    for (int i = 1; i <= numNode; ++i){
        int prv = find(minDist[0][i]);
        int value = find(minTime - minDist[1][i] - length);

        ft.upd(prv, -1);
        ans += ft.query(value);
        ft.upd(prv, 1);
    }
    cout << ans;
}
signed main(){
    #define name "Whisper"
    cin.tie(nullptr) -> sync_with_stdio(false);
    //freopen(name".inp", "r", stdin);
    //freopen(name".out", "w", stdout);
    process();
    return (0 ^ 0);
}

• Subtask 1: 8 / 8
• Subtask 2: 16 / 16
• Subtask 3: 29 / 29
• Subtask 4: 47 / 47