Submission #1164103

#	Time	Username	Problem	Language	Result	Execution time	Memory
1164103		Syrius	Construction Project 2 (JOI24_ho_t2)	C++20	100 / 100	369 ms	29944 KiB

Main

#include <bits/stdc++.h>
using namespace std;

#define int long long
#define ll long long
#define ff first
#define ss second
#define pint pair < int , int >
#define fast ios_base::sync_with_stdio(NULL); cin.tie(NULL)
typedef vector < int > vint;

const int inf = 1e9 + 9;
const int mxn = 2e5 + 2;
const int mod = 1e9 + 7;

int s , l , t , k , n , m;
int dis[2][mxn];
vector < vector < pint > > adj(mxn);

void build(int start , int id) {

    priority_queue < pint > q;
    q.push({0 , start});

    while (!q.empty()) {
        pint p = q.top();
        q.pop();
        int u = p.ss;
        
        if (dis[id][u] != -1) continue;
        dis[id][u] = -p.ff;

        for (pint v : adj[u]) {
            q.push({p.ff - v.ss , v.ff});
        }
    }
}

signed main() {

    cin >> n >> m;
    cin >> s >> t >> l >> k;

    for (int i = 0; i < m; i++) {
        int a , b , c;
        cin >> a >> b >> c;
        adj[a].push_back({b , c});
        adj[b].push_back({a , c});
    }

    for (int j = 0; j < 2; j++) {
        for (int i = 1; i <= n; i++) {
            dis[j][i] = -1;
        }
    }

    build(s , 0);
    build(t , 1);

    sort(dis[1] + 1 , dis[1] + 1 + n);

    if (dis[0][t] <= k && dis[0][t] != -1) {
        cout << n * (n - 1) / 2 << '\n';
        return 0;
    }

    int left = 1;
    for (int i = 1; i <= n; i++) {
        if (dis[1][i] != -1) {
            left = i;
            break;
        }
    }

    int ans = 0;
    for (int i = 1; i <= n; i++) {
        if (dis[0][i] == -1) continue;
        int L = left , R = n;
        while (L != R) {
            int M = (L + R) / 2;
            // cout << M << ' ';
            if (dis[1][M] + dis[0][i] + l <= k) L = M + 1;
            else R = M;
        }
        if (dis[1][R] + dis[0][i] + l <= k) ans++;
        // cout << R << '\n';
        ans += R - left;
    }

    cout << ans << '\n';
    return 0;

}

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